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{{Infobox military conflict
| conflict          = Fourth Crusade
| partof            = the [[Crusades]]
| image             = ConquestOfConstantinopleByTheCrusadersIn1204.jpg
| image_size        = 300px
| caption           = A 15th-century miniature depicting the conquest of Constantinople by the Crusaders in 1204
| date              = 1202–1204
| place             = [[Balkans]], [[Anatolia]], [[Dalmatia]]
| result            = See {{section link||Aftermath}}
| combatant1        = Crusaders from:{{ublist
 | [[France in the Middle Ages|Kingdom of France]]
 | [[Holy Roman Empire]]
 | [[Republic of Venice]]
}}
| combatant2        = '''In Europe:''' {{Plainlist|
*[[Byzantine Empire under the Angelos dynasty|Byzantine Empire]]
*[[Kingdom of Hungary (1000–1301)|Kingdom of Hungary]]
*[[Croatia in personal union with Hungary|Kingdom of Croatia]]
'''Holy Land:'''
*[[Ayyubid dynasty]]
}}
| commander1        = {{plainlist|
* [[Boniface I of Montferrat]]
* [[Enrico Dandolo]]
* [[Theobald III of Champagne]]{{Natural Causes}}
* [[Baldwin IX of Flanders]]
* [[Louis I, Count of Blois|Louis of Blois]]
* [[Hugh IV of Saint-Pol]]
* [[Conrad of Halberstadt]]
* [[Martin of Pairis]]
* [[Conon de Béthune]]
* [[Alexios IV Angelos]]{{executed}}}}
| commander2        = {{plainlist|
* [[Alexios III Angelos]]
* [[Alexios V Doukas]]{{Executed}}}}
----
[[Al-Adil]]
| strength1         = {{ubl|4,000-5,000 knights|8,000 infantry|300 siege weapons|10,000 sailors and marines|60 war galleys|100 horse transports|50 troop transports}}
| strength2         = {{ubl|10,000 Byzantine infantry and city militias|5,000 Varangians|20 war galleys}}
| campaignbox       = {{Campaignbox Crusades}}
}}
{{Campaignbox Fourth Crusade}}

The '''Fourth Crusade''' (1202–1204) was a [[Latin Christian]] armed expedition called by [[Pope Innocent III]]. The stated intent of the expedition was to recapture the Muslim-controlled city of [[Jerusalem]], by first defeating the powerful Egyptian [[Ayyubid Sultanate]]. However, a sequence of economic and political events culminated in the Crusader army's 1202 [[siege of Zara]] and the 1204 [[sack of Constantinople]], rather than the conquest of Egypt as originally planned. This led to the [[Partitio terrarum imperii Romaniae|partition of the Byzantine Empire]] by the Crusaders and their Venetian allies, leading to a period known as the ''[[Frankokratia]]'' ("Rule of the Franks" in Greek).

In 1201, the [[Republic of Venice]] contracted with the Crusader leaders to build a dedicated fleet to transport their invasion force. However, the leaders greatly overestimated the number of soldiers who would embark from Venice, since many sailed from other ports, and the army that appeared could not pay the contracted price. In lieu of payment, the Venetian Doge [[Enrico Dandolo]] proposed that the Crusaders back him in attacking the rebellious city of [[Zara, Dalmatia|Zara]] (Zadar) on the eastern Adriatic coast. This led in November 1202 to the [[Siege of Zara|siege and sack of Zara]], the first attack against a Catholic city by a Catholic Crusader army, despite [[Pope Innocent III]]'s calls for the Crusaders not to attack fellow Christians. The city was then brought under Venetian control. When the Pope heard of this, he temporarily [[excommunicated]] the Crusader army.

In January 1203, en route to Jerusalem, the Crusader leadership entered into an agreement with the Byzantine prince [[Alexios IV Angelos|Alexios Angelos]] to divert their main force to [[Constantinople]] and restore his deposed father [[Isaac II Angelos]] as emperor, who would then add his support to their invasion of Jerusalem. On 23 June 1203, the main Crusader army reached Constantinople, while other contingents (perhaps a majority of all crusaders) continued to [[Acre (city)|Acre]].

In August 1203, following the [[Siege of Constantinople (1203)|siege of Constantinople]], Alexios was crowned co-emperor. However, in January 1204 he was deposed by a popular uprising, depriving the Crusaders of their promised bounty payments. Following the murder of Alexios on 8 February, the Crusaders decided on the outright conquest of the city. In April 1204, they captured and plundered the city's enormous wealth. Only a handful of the Crusaders continued to the Holy Land thereafter. Several prominent Crusaders, including [[Enguerrand II of Boves]], [[Simon de Montfort, 5th Earl of Leicester]] and [[Guy of Vaux-de-Cernay]], among others, disagreed with the attacks on Zara and Constantinople, refused to take part in them and left the crusade.

The conquest of Constantinople was followed by the fragmentation of the [[Byzantine Empire]] into three states centered in [[Empire of Nicaea|Nicaea]], [[Empire of Trebizond|Trebizond]] and [[Despotate of Epirus|Epirus]]. The Crusaders then founded several new Crusader states, known as ''[[Frankokratia]]'', in former Roman territory, largely hinged upon the [[Latin Empire of Constantinople]]. The presence of the Latin Crusader states almost immediately led to war with the [[Nicaean-Latin wars|Byzantine successor states]] and with the [[Bulgarian-Latin wars|Bulgarian Empire]]. The Nicaean Empire eventually [[Reconquest of Constantinople|recovered Constantinople]] and restored the Byzantine Empire in July 1261.

The Fourth Crusade is considered to have solidified the [[East–West Schism]]. The crusade dealt an irrevocable blow to the Byzantine Empire, contributing to [[decline of the Byzantine Empire|its decline]] and fall as all the unstable governments in the region, the Sack of Constantinople, and the thousands of deaths had left the region depleted of soldiers, resources, people and money, leaving it vulnerable to attack. Additionally, the empire had badly shrunk as it lost control of most of the Balkans, Anatolia, and Aegean islands. This made the restored empire both territorially diminished and vulnerable to [[Byzantine–Ottoman wars|invasions]] from the expanding [[Ottoman Sultanate|Ottomans]] in the following centuries, to which the Byzantines ultimately succumbed [[Fall of Constantinople|in 1453]].

== Background ==
=== Loss of Jerusalem to the truce of 1198 ===
In 1187, the [[Ayyubid Sultanate]] under [[Saladin]] conquered most of the [[Crusader states]] in the Levant. Jerusalem was lost to the Ayyubids as a result of the [[Siege of Jerusalem (1187)|siege of Jerusalem]] in 1187 leading to the calling of the [[Third Crusade]].<ref>[[John Julius Norwich]], ''Byzantium: The Decline and Fall'', (1995; repr., London: Folio Society, 2003), 169</ref> The Crusader states were then reduced by Saladin to little more than three cities along the coast of the Mediterranean Sea: [[Tyre, Lebanon|Tyre]], [[Tripoli, Lebanon|Tripoli]] and [[Antioch]].<ref>{{cite book |first=Hans Eberhard |last=Mayer |page=136 |title=The Crusades |year=1988 |publisher=Oxford University Press |isbn=0-19-873097-7}}</ref>

The [[Third Crusade]] (1189–1193) was launched in response to the fall of Jerusalem, with the goal of recovering the city. It successfully reclaimed an extensive territory, effectively reestablishing the [[Kingdom of Jerusalem]]. Although Jerusalem itself was not recovered, the important coastal towns of [[Acre, Israel|Acre]] and [[Jaffa]] were. On 2 September 1192, the [[Treaty of Jaffa (1192)|Treaty of Jaffa]] was signed with Saladin, bringing the crusade to an end. The truce would last for three years and eight months.<ref name=Kedar>{{citation |author=[[Benjamin Z. Kedar]] |chapter=The Fourth Crusade's Second Front |editor1=A. Laiou |title=Urbs Capta: The Fourth Crusade and its Consequences |location=Paris |year=2005 |pages=89–101 |publisher=Lethielleux}}.</ref>

The crusade had also been marked by a significant escalation in longstanding tensions between the feudal states of western Europe and the Byzantine Empire.<ref>{{cite book |last=Haldon |first=John |title=Byzantium at War |url=https://archive.org/details/byzantiumatwarad00hald_817 |url-access=limited |publisher=Osprey |location=Oxford |year=2002 |page=[https://archive.org/details/byzantiumatwarad00hald_817/page/n84 87]}}</ref>{{sfn|Phillips|2004|p=4}} During the crusade, [[Frederick I, Holy Roman Emperor|Emperor Frederick I Barbarossa]] had almost besieged Constantinople because of the failure of the Byzantine government and Emperor, [[Isaac II Angelos]], to provide him with safe passage across the [[Dardanelles]] because Isaac was busy fighting a pretender named [[Theodore Mangaphas]]. The Byzantines for their part suspected him of conspiring with the breakaway Byzantine provinces of [[Kingdom of Serbia (medieval)|Serbia]] and [[Second Bulgarian Empire|Bulgaria]] as Frederick Barbarossa was on friendly terms with Grand Prince [[Stefan Nemanja]] of Serbia and also got a letter getting support and fealty from Tsar [[Ivan Asen I]] of Bulgaria. King [[Richard I of England|Richard I Lionheart of England]] also seized the breakaway Eastern Roman [[Theme of Cyprus|province of Cyprus]]. Rather than return it to the Empire (and realizing his inability to govern it), he gave the island to [[Guy of Lusignan]], the former king of Jerusalem, who lost the crown to a former Eastern Roman ally, [[Conrad of Montferrat]].<ref>{{Cite web |title=Templar Rule on Cyprus 1191–1192 |url=http://defenderofjerusalem.com/templar-rule-on-cyprus-.html |access-date=2022-08-10 |website=HeSchrader}}</ref>

Saladin died on 4 March 1193, before the expiration of the truces, and his empire was contested and divided between three of his sons and two of his brothers. The new ruler of the Kingdom of Jerusalem, [[Henry II of Champagne]], signed an extension of the truce with Egyptian Sultan [[al-Aziz Uthman]]. In 1197, the peace was interrupted by the arrival of the [[German Crusade]] of 1197. Without the permission of Henry, the Germans attacked the territory of [[al-Adil I]] of Damascus, who responded by attacking Jaffa. The sudden death of Henry prevented the relief of the port and the city was taken by force. The Germans did, however, succeed in capturing [[Beirut]] in the north.<ref name=Kedar />

Henry was succeeded by [[Aimery of Cyprus]], who signed a truce with al-Adil of five years and eight months on 1 July 1198. The truce preserved the status quo: Jaffa remained in Ayyubid hands, but its destroyed fortifications could not be rebuilt; Beirut was left to the crusaders; and [[Sidon]] was placed under a revenue-sharing condominium. Before the expiration of the new truce on 1 March 1204, al-Adil succeeded in uniting the former empire of Saladin, acquiring Egypt in 1200 and [[Aleppo]] in 1202. As a result, his domains almost completely surrounded the diminished Crusader states.<ref name=Kedar />

=== Constantinople ===
Constantinople had been in existence for 874 years at the time of the Fourth Crusade and was the largest and most sophisticated city in Christendom. Almost alone amongst major medieval urban centres, it had retained the civic structures, public baths, forums, monuments, and aqueducts of classical Rome in working form. At its height, the city was home to an estimated population of about half a million people{{sfn|Nicolle|2011|p=15}} protected by 20&nbsp;km (around 13 miles) of triple walls.<ref>{{cite book |first=Si |last=Sheppard |page=6 |title=Constantinople AD 717–18 |date=2020 |publisher=Bloomsbury |isbn=978-1-4728-3692-2}}</ref> Its planned location made Constantinople not only the capital of the surviving eastern part of the Roman Empire but also a commercial centre that dominated trade routes from the Mediterranean to the Black Sea,<ref name="Jean-Louis Larcade page 15">Norman Davies, p. 311, "Vanished Kingdoms. The History of Half-forgotten Europe", {{ISBN|978-0-141-04886-4}}</ref> China, India and Persia.<ref>{{cite book |last=Sherrard |first=Philip |title=Byzantium |publisher=Time-Life |year=1967 |pages=42–43}}</ref> As a result, it was both a rival and a tempting target for the aggressive new states of the west, notably the [[Republic of Venice]].

In 1195, the [[Byzantine Emperor]] [[Isaac II Angelos]] was deposed in favour of his brother by a palace coup. Ascending as [[Alexios III Angelos]], the new emperor had his brother [[political mutilation in Byzantine culture|blinded]] (a traditional punishment for treason, considered more humane than execution) and exiled. Ineffectual on the battlefield, Isaac had also proven to be an incompetent ruler who had let the treasury dwindle and outsourced the navy to the Venetians. His actions in wastefully distributing military weapons and supplies as gifts to his supporters had undermined the empire's defenses.<ref>John Julius Norwich, ''Byzantium: The Decline and Fall'', (1995; repr., London: Folio Society, 2003)</ref> The new emperor was to prove no better. Anxious to shore up his position, Alexios bankrupted the treasury. His attempts to secure the support of semi-autonomous border commanders undermined central authority. He neglected his crucial responsibilities for defence and diplomacy. The emperor's chief admiral (his wife's brother-in-law), [[Michael Stryphnos]], reportedly sold the fleet's equipment down to the very nails to enrich himself.<ref>{{ODB | last = Brand | first = Charles M. | last2= Cutler | first2= Anthony | title = Stryphnos, Michael | page= 1968}}</ref><ref>{{Recherches sur les institutions byzantines | volume = I | chapter = Le Drongaire de la flotte, le Grand drongaire de la flotte, le Duc de la flotte, le Mégaduc | pages = 535–562 }}</ref>

== Rendezvous at Venice ==
[[File:C croisade4 flotte.jpg|thumb|[[Venetian Navy]] landing in Constantinople, from a XV Century miniature]]
[[Pope Innocent III]] succeeded to the papacy in January 1198, and the preaching of a new crusade became the prime goal of his pontificate, expounded in his bull ''[[Post miserabile]]''.<ref name="Runciman">{{cite book |last=Runciman |first=Steven |title=A History of the Crusades: The Kingdom of Acre and the Later Crusades |volume=3 |year=1954 |isbn=0-14-013705-X |pages=107–111 |publisher=Penguin |author-link=Steven Runciman}}</ref> His call was largely ignored by the European monarchs: the Germans were struggling against Papal power, and [[Kingdom of England|England]] and [[France in the Middle Ages|France]] were still engaged in [[Capetian–Plantagenet rivalry|warfare against each other]]. However, due to the preaching of [[Fulk of Neuilly]], in November Count Thibaut of Champagne hosted a knightly tournament at his castle in Écry-sur-Aisne. The event, though tinged with mourning for the recent death of Thibaut's uncle, King Richard I of England, became a turning point. During the festivities, Thibaut vowed to abandon martial games and instead dedicate his weapons to God's service, declaring his intention to join a crusade.

By early 1200, a council of leading crusader barons—including Thibaut, Louis of Blois, and Baldwin of Flanders—convened at Soissons to organize the expedition. They agreed to avoid the overland route through the Byzantine Empire and instead sail to Egypt, mirroring Richard I's strategy. To secure ships, the lords appointed a six-member committee, among them Geoffrey of Villehardouin (later the crusade's chronicler), to negotiate contracts with maritime powers.

Thibaut was elected leader, but his sudden death in 1201 led to Boniface of Montferrat—brother of Conrad of Montferrat, who had died defending Tyre—assuming command. The committee ultimately secured a fleet through Venice. 
<ref>{{Cite book |last=Madden |first=Thomas F. |title=The concise history of the crusades |date=2014 |publisher=Rowman & Littlefield |isbn=978-1-4422-1575-7 |edition=Third |location=Lanham |page=95 |language=en}}</ref>

Earlier crusades focused on the [[Land of Israel]] had involved the slow movement of large and disorganised land hosts across a generally hostile [[Anatolia]]. Egypt was now the dominant Muslim power in the eastern Mediterranean but also a major trading partner of Venice.<ref>Encyclopædia Britannica 15th ed., p. 306, Macropaedia Vol. 5</ref> An attack on Egypt would clearly be a maritime enterprise, requiring the creation of a fleet. Genoa was uninterested, but in March 1201 negotiations were opened with the doge of Venice, [[Enrico Dandolo]] who agreed to transport 33,500 crusaders, a very ambitious number. This was the moment, according to him, for the Venetian Republic to gain wealth, prestige, land, and trading routes in the [[Levant|Holy Land]]. This agreement required a full year of preparation on the part of the Venetians to build numerous ships and train the sailors who would man them, all the while curtailing the city's commercial activities. The crusading army was expected to consist of 4,500 knights (as well as 4,500 horses), 9,000 squires, and 20,000 foot-soldiers.<ref>'The compact with the Venetians. Villehardouin: Conquête de Constantinople, ch. iv, v, vi, Nos. 18, 24, 30 Old French.</ref> The majority of the crusading army that set out from [[Venice]] in early October 1202 originated from areas within France. It included men from [[Blois]], [[Champagne, France|Champagne]], [[Amiens]], [[County of Saint-Pol|Saint-Pol]], the [[Île-de-France]], and [[Duchy of Burgundy|Burgundy]]. Several other regions of Europe sent substantial contingents as well, such as [[Flanders]] and [[Montferrat]]. Other notable groups came from the [[Holy Roman Empire]], including the men under [[Martin of Pairis|Martin]], abbot of [[Pairis Abbey]] <!--Pairis is not Paris--> and Bishop [[Conrad of Halberstadt]], together in alliance with the Venetian soldiers and sailors led by the [[Doge of Venice|doge]], [[Enrico Dandolo]]. The crusade was to be ready to sail on 24 June 1203 and make directly for the Ayyubid capital, [[Cairo]]. This agreement was ratified by Pope Innocent, with a solemn ban on attacks on Christian states.<ref name="Hughes">Hughes, Philip. "Innocent III and the Latin East", ''[http://www.ewtn.com/library/CHISTORY/HUGHHIST.TXT History of the Church] {{Webarchive|url=https://web.archive.org/web/20181223191523/http://www.ewtn.com/library/CHISTORY/HUGHHIST.TXT |date=2018-12-23 }}'' (Sheed & Ward, 1948), vol. 2, pp. 370–372.</ref>

== Diversion ==
=== Attack on Zara ===
{{Main|Siege of Zara}}
[[File:Pallucchini Tintoretto 590 1.jpg|upright=1.35|thumb|right|The crusaders conquering the City of Zadar, painted by [[Tintoretto]] ]]

There was no binding agreement among the crusaders that all should sail from Venice. Accordingly, many chose to sail from other ports, particularly [[Flanders]], [[Marseille]], and [[Genoa]]. By May 1202, the bulk of the crusader army was collected at Venice, although with far smaller numbers than expected: about 12,000 (4,000–5,000 knights and 8,000 foot soldiers) instead of 33,500.{{sfn|Queller|Madden|1997|p=232}} The Venetians had performed their part of the agreement: there awaited 50 war galleys and 450 transports{{snd}}enough for three times the assembled army.{{sfn|Queller|Madden|1997|p=17}} The Venetians, under their aged and blind Doge Dandolo, would not let the crusaders leave without paying the full amount agreed to, originally 85,000 silver [[Mark (money)|marks]]. The crusaders could only initially pay 35,000 silver marks. The Doge threatened to keep them interned unless full payment was made so a further 14,000 marks were collected, and that only by reducing the crusaders to extreme poverty.<ref>Robert de Clari, La Prise de Constantinople, xi–xii, in Hopf, Chroniques Greco-Romaines, pp. 7–9. Old French.</ref> This was disastrous to the Venetians, who had halted their commerce for a great length of time to prepare this expedition. In addition, about 14,000 men or as many as 20–30,000 men (out of Venice's population of 60–100,000 people) were needed to man the entire fleet, placing further strain on the Venetian economy.{{sfn|Queller|Madden|1997|p=17}}{{sfn|Phillips|2004|p=57}}

Dandolo and the Venetians considered what to do with the crusade. It was too small to pay its fee, but disbanding the force gathered would harm Venetian prestige and cause significant financial and trading loss. Dandolo, who joined the crusade during a public ceremony in the church of [[San Marco di Venezia]], proposed that the crusaders pay their debts by intimidating many of the local ports and towns down the Adriatic, culminating in an attack on the port of [[Zadar|Zara]] in [[Dalmatia]].<ref>Zara is the today the city of [[Zadar]] in [[Croatia]]; it was called "Jadera" in [[Latin]] documents and "Jadres" by [[France|French]] crusaders. The Venetian (Italian) "Zara" is a later derivation of the contemporary vernacular "Zadra".</ref> The city had been dominated economically by Venice throughout the 12th century but had rebelled in 1181 and allied itself with [[King Emeric]] of [[Kingdom of Hungary|Hungary]] and [[King of Croatia|Croatia]].{{sfn|Queller|Madden|1997|p={{page needed|date=December 2024}}}}<ref>[https://www.britannica.com/EBchecked/topic/185757/Emeric Emeric (king of Hungary)]. Britannica Online Encyclopedia.</ref> Subsequent Venetian attempts to recover control of Zara had been repulsed, and by 1202 the city was economically independent, under the protection of the King.{{sfn|Phillips|2004|pp=110–111}}

King Emeric was Catholic and had himself taken the cross in 1195 or 1196. Many of the crusaders were opposed to attacking Zara, and some, including a force led by the elder [[Simon de Montfort, 5th Earl of Leicester|Simon V de Montfort]], refused to participate altogether and returned home or went to the Holy Land on their own. While the Papal legate to the Crusade, Cardinal [[Peter of Capua the Elder|Peter of Capua]], endorsed the move as necessary to prevent the crusade's complete failure, the Pope was alarmed at this development and wrote a letter to the crusading leadership threatening [[excommunication]].<ref name="Hughes" />

In 1202, Pope Innocent III, despite wanting to secure papal authority over the Roman [[Eastern Orthodox Church|Orthodox Church]], forbade the crusaders of Western Christendom from committing any atrocious acts against their Christian neighbours.<ref>{{cite book |last=Hindley |first=Geoffrey |title=The Crusades: A History of Armed Pilgrimage and Holy War |url=https://archive.org/details/crusadeshistoryo00hind |url-access=registration |publisher=Carroll & Graf |location=New York |year=2003 |pages=[https://archive.org/details/crusadeshistoryo00hind/page/143 143], 152 |isbn=978-0-7867-1105-5}}</ref> However, this letter, delivered by [[Peter of Lucedio]], may not have reached the army in time. The bulk of the army arrived at Zara on 10–11 November 1202 and the attack proceeded. The citizens of Zara made reference to the fact that they were fellow Catholics by hanging banners marked with crosses from their windows and the walls of the city, but nevertheless the city fell on 24 November 1202 after a brief siege. There was extensive pillaging, and the Venetians and other crusaders came to blows over the division of the spoils. Order was achieved, and the leaders of the expedition agreed to winter in Zara, while considering their next move.<ref>{{cite book |last=Runciman |first=Stephen |title=A History of the Crusades – the Kingdom of Arce and the Later Crusades |publisher=Cambridge University Press |year=1975 |page=115 |isbn=0-521-20554-9}}</ref> The fortifications of Zara were demolished by the Venetians.

When Innocent III heard of the sack, he sent a letter to the crusaders excommunicating them and ordering them to return to their [[Crusade vow|holy vows]] and head for Jerusalem. Out of fear that this would dissolve the army, the leaders of the crusade decided not to inform their followers of this. Regarding the Crusaders as having been coerced by the Venetians, in February 1203 he rescinded the excommunications against all non-Venetians in the expedition.<ref name="Runciman98">Runciman, Steven. ''The Kingdom of Acre and the Later Crusades,'' (1954; repr., London: Folio Society, 1994), 98</ref>

=== Decision to go to Constantinople ===
[[File:Gustave dore crusades dandolo preaching the crusade.jpg|upright=1.35|thumb|right|''Dandolo Preaching the Crusade'' by [[Gustave Doré]]]]

The commercial rivalry between the Republic of Venice and the Byzantine Empire and the living memory of the [[Massacre of the Latins]] did much to exacerbate the feeling of animosity among the Venetians towards the [[Byzantine Greeks]]. According to the [[Novgorod First Chronicle|Chronicle of Novgorod]] Doge Enrico Dandolo had been blinded by the Emperor [[Manuel I Komnenos]] the Great while part of an embassy to Constantinople in 1171, and accordingly held personal enmity towards the Byzantines.<ref>{{Cite book |url=https://books.google.com/books?id=sk9lvXUMHpYC&q=%22recorded+in+the+chronicle+of+novgorod%22&pg=PA64 |title=Enrico Dandolo and the Rise of Venice |first=Thomas F. |last=Madden |year=2006 |publisher=Johns Hopkins University Press |isbn=978-0-8018-9184-7 |via=Google Books}}</ref>

[[Boniface I of Montferrat|Boniface of Montferrat]], meanwhile, had left the fleet before it sailed from Venice, to visit his cousin [[Philip of Swabia]]. The reasons for his visit are a matter of debate; he may have realized the Venetians' plans and left to avoid excommunication, or he may have wanted to meet with the Roman prince [[Alexios IV Angelos]], Philip's brother-in-law and the son of the recently deposed Roman emperor [[Isaac II Angelos]]. Alexios IV had recently fled to Philip in 1201 but it is unknown whether or not Boniface knew he was at Philip's court. There, Alexios IV offered to pay the entire debt owed to the Venetians, give 200,000 silver marks to the crusaders, 10,000 Byzantine professional troops for the Crusade, the maintenance of 500 knights in the Holy Land, the service of the Byzantine navy to transport the Crusader Army to Egypt, and the placement of the [[Eastern Orthodox Church]] under the authority of the Pope, if they would sail to Constantinople and topple the reigning emperor [[Alexios III Angelos]], brother of Isaac II. This offer, tempting for an enterprise that was short on funds, reached the leaders of the Crusade on 1 January 1203 as they wintered at Zara.<ref>{{cite book |first=Jean |last=Richard |page=247 |title=The Crusades c. 1071 – c. 1291 |year=1999 |publisher=Cambridge University Press |isbn=0-521-62566-1}}</ref> Doge Dandolo was a fierce supporter of the plan; however, in his earlier capacity as an ambassador to the Byzantine Empire and someone who knew the finer details of how the empire's politics worked, it is likely he knew the promises were false and there was no hope of any Byzantine emperor raising the money promised, let alone raising the troops and giving the church to the Holy See. Count Boniface agreed and Alexios IV returned with the Marquess to rejoin the fleet at [[Corfu]] after it had sailed from Zara. Most of the rest of the crusade's leaders, encouraged by bribes from Dandolo,<ref name="Runciman98" /> eventually accepted the plan as well. However, there were dissenters. Led by [[Renaud of Montmirail]], those who refused to take part in the scheme to attack Constantinople sailed on to Syria.<ref name="Runciman98" /> The remaining fleet of 60 [[war galley]]s, 100 [[Horse transports in the Middle Ages|horse transports]], and 50 large [[Troopship|transports]] (the entire fleet was manned by 10,000 Venetian oarsmen and marines) sailed in late April 1203.{{sfn|Phillips|2004|p=269}} In addition, 300 siege engines were brought along on board the fleet.{{sfn|Phillips|2004|p=113}} Hearing of their decision, the Pope hedged and issued an order against any more attacks on Christians unless they were actively hindering the Crusader cause, but he did not condemn the scheme outright.<ref>Runciman, Steven. ''The Kingdom of Acre and the Later Crusades'', (1954; repr., London: Folio Society, 1994), 99</ref>

=== Defences of Constantinople ===
When the Fourth Crusade arrived at Constantinople on 23 June 1203, the city had a population of approximately 500,000 people,{{sfn|Nicolle|2011|p=49}} a garrison of 15,000 men (including 5,000 [[Varangians]]), and a fleet of 20 galleys.{{sfn|Queller|Madden|1997|p=185}}{{sfn|Phillips|2004|pp=157, 159}}<ref name="Treadgold164">[[Warren Treadgold|Treadgold, W.]] ''A Concise History of Byzantium'', 187</ref> For both political and financial reasons, the permanent garrison of Constantinople had been limited to a relatively small force, made up of elite guards and other specialist units. At previous times in East Roman and Byzantine history when the capital had come under direct threat, it had been possible to assemble reinforcements from frontier and provincial forces.<ref>{{cite book |first=Stephen |last=Turnbull |page=35 |title=The Walls of Constantinople AD 324–1453 |date=22 October 2004 |publisher=Bloomsbury |isbn=978-1-84176-759-8}}</ref> On this occasion, the suddenness of the danger posed by the Fourth Crusade put the defenders at a serious disadvantage.{{sfn|Nicolle|2011|p=41}} The main objective of the crusaders was to place Alexios IV on the Byzantine throne so that they could receive the rich payments he had promised them. [[Conon of Bethune]] delivered this ultimatum to the Lombard envoy sent by the Emperor [[Alexios III Angelos]], who was the pretender's uncle and had seized the throne from the pretender's father Isaac II. The citizens of Constantinople were not concerned with the cause of the deposed emperor and his exiled son; hereditary right of succession had never been adopted by the empire and a palace coup between brothers was not considered illegitimate in the way it would have been in the West. First the crusaders attacked and were repulsed from the cities of [[Chalcedon]] and [[Üsküdar#Chrysopolis|Chrysopolis]], suburbs of the great city. They won a cavalry skirmish in which they were outnumbered, defeating 500 Byzantines with just 80 Frankish knights.{{sfn|Phillips|2004|p=162}}

=== Siege of July 1203 ===
{{Main|Siege of Constantinople (1203)}}
[[File:Crusaders attack Constantinople.jpg|thumb|right|upright=1.15|The Crusader attack on Constantinople, from a Venetian manuscript of Geoffrey de Villehardouin's history, {{circa|1330}}]]
To take the city by force, the crusaders first needed to cross the [[Bosphorus]]. About 200 ships, horse transports, and [[galley]]s delivered the crusading army across the narrow strait, where Alexios III had lined up the Byzantine army in battle formation along the shore, north of the suburb of Galata. The Crusader knights charged straight out of the horse transports, and the Byzantine army fled south. The Crusaders followed and attacked the [[Galata Tower (old)|Tower of Galata]], which held the northern end of the massive chain that blocked access to the [[Golden Horn]]. The Tower of Galata held a garrison of mercenary troops of English, Danish, and Italian origin.<ref>{{cite book |last1=Andrea |first1=Alfred |author-link=Alfred J. Andrea|title=Contemporary Sources For The Fourth Crusade |pages=191–192}}</ref> On 6 July the largest ship in the crusaders' fleet, the ''Aquila'' (Eagle), broke the chain. A section of it was then sent to Acre to boost the defences in the Holy Land.<ref name=Kedar />

As the crusaders laid siege to the Tower of Galata, the defenders routinely attempted to sally out with some limited success, but often suffered bloody losses. On one occasion the defenders sallied out but were unable to retreat back to the safety of the tower in time, the Crusader forces viciously counterattacked, with most of the defenders being cut down or drowning in the Bosporus in their attempts to escape.<ref>{{cite book |last1=Andrea |first1=Alfred |title=Contemporary Sources For The Fourth Crusade |page=193}}</ref> The tower was swiftly taken as a result. The Golden Horn now lay open to the Crusaders, and the Venetian fleet entered. The Crusaders sailed alongside Constantinople with 10 galleys to display the would-be Alexios IV, but from the [[walls of Constantinople|walls of the city]] citizens taunted the puzzled crusaders, who had been led to believe that they would rise up to welcome the young pretender Alexios as a liberator.{{sfn|Phillips|2004|p=164}}

On 11 July, the Crusaders took positions opposite the [[Palace of Blachernae]] on the northwest corner of the city. Their first attacks were repulsed, but on 17 July, with four divisions attacking the land walls while the Venetian fleet attacked the sea walls from the Golden Horn, the Venetians took a section of the wall of about 25 towers, while the Varangian guard held off the Crusaders on the land wall. The Varangians shifted to meet the new threat, and the Venetians retreated under the screen of fire. The fire destroyed about {{convert|120|acre|km2}} of the city and left some 20,000 people homeless.{{sfn|Phillips|2004|p=176}}

Alexios III finally took offensive action, leading 17 divisions from the St. Romanus Gate, vastly outnumbering the crusaders. Alexios III's army of about 8,500 men faced the Crusaders' seven divisions (about 3,500 men), but his courage failed, and the Byzantine army returned to the city without a fight.{{sfn|Phillips|2004|p=177}} The unforced retreat and the effects of the fire greatly damaged morale, and the disgraced Alexios III abandoned his subjects, slipping out of the city and fleeing to [[Mosynopolis]] in [[Thrace]].<ref name="Runciman100">Runciman, Steven. ''The Kingdom of Acre and the later Crusades'', (1954; repr., London: Folio Society, 1994), 100</ref> The Imperial officials quickly deposed their runaway emperor and restored Isaac II, robbing the crusaders of the pretext for attack.<ref name="Runciman100" /> The crusaders were now in the quandary of having achieved their stated aim while being debarred from the actual objective, namely the reward that the younger Alexios had (unbeknownst to the Romans) promised them. The crusaders insisted that they would only recognize the authority of Isaac II if his son was raised to co-emperor, and on 1 August the latter was crowned as Alexios Angelos IV, co-emperor.<ref name="Runciman100" />

=== Reign of Alexios IV ===
[[File:PriseDeConstantinople1204PalmaLeJeune.JPG|thumb|upright=1.15|Capture of Constantinople by the Fourth Crusade in 1204]]
Alexios IV realised that his promises were hard to keep. Alexios III had managed to flee with 1,000&nbsp;pounds of gold and some priceless jewels, leaving the imperial treasury short on funds. At that point the young emperor ordered the destruction and melting of valuable Roman icons in order to extract their gold and silver, but even then he could only raise 100,000 silver marks. In the eyes of all Greeks who knew of this decision, it was a shocking sign of desperation and weak leadership, which deserved to be punished by God. The Byzantine historian [[Nicetas Choniates]] characterized it as "the turning point towards the decline of the Roman state".{{sfn|Phillips|2004|pp=221–257}}

Forcing the populace to destroy their icons at the behest of an army of foreign schismatics did not endear Alexios IV to the citizens of Constantinople. In fear of his life, the co-emperor asked the crusaders to renew their contract for another six months, to end by April 1204. Alexios IV then led 6,000 men from the Crusader army against his rival Alexios III in Adrianople.{{sfn|Phillips|2004|p=209}} During the co-emperor's absence in August, rioting broke out in the city and a number of Latin residents were killed. In retaliation armed Venetians and other crusaders entered the city from the Golden Horn and attacked a [[mosque]] (Constantinople at this time had a sizable Muslim population), which was defended by Muslim and Byzantine Greek residents {{citation needed|date=February 2018}}. In order to cover their retreat the Westerners instigated the "Great Fire", which burnt from 19 to 21 August, destroying a large part of Constantinople and leaving an estimated 100,000 homeless.

In January 1204, the blinded and incapacitated Isaac II died, probably of natural causes.{{sfn|Phillips|2004|pp=221–257}} Opposition to his son and co-emperor Alexios IV had grown during the preceding months of tension and spasmodic violence in and around Constantinople. The [[Byzantine Senate]] elected a young noble [[Nicolas Canabus]] as emperor, in what was to be one of the last known acts of this ancient institution. However he declined the appointment and sought church sanctuary.<ref>''Chambers's Encyclopaedia'', vol. II, London, 1868, p. 471</ref>

A nobleman [[Alexios Doukas]] (nicknamed Mourtzouphlos) became the leader of the anti-crusader faction within the Byzantine leadership. While holding the court rank of ''protovestilarios'', Doukas had led Byzantine forces during the initial clashes with the crusaders, winning respect from both military and populace. He was accordingly well-placed to move against the increasingly isolated Alexios IV, whom he overthrew, imprisoned, and had strangled in early February. Doukas then was crowned as Emperor Alexios V Doukas Mourtzouphlos. He immediately moved to have the city fortifications strengthened and summoned additional forces to the city.{{sfn|Nicolle|2011|pp=25, 65}}

=== War against Alexios V ===
[[File:Frammenti di mosaico pavimentale del 1213, 09.JPG|thumb|upright=1.2|Venetian mosaic from 1213 depicting the fall of Constantinople]]

The crusaders and Venetians, incensed at the murder of their supposed patron, demanded that Mourtzouphlos honour the contract that Alexios IV had promised. When the emperor refused, the Crusaders assaulted the city once again. On 8 April Alexios V's army put up a strong resistance, which did much to discourage the Crusaders. The Byzantines hurled large projectiles onto the enemy siege engines, shattering many of them. Bad weather conditions were a serious hindrance to the crusaders. A fierce wind blew from the shore and prevented most of the ships from drawing close enough to the walls to launch an assault. Only five of the wall's towers were actually engaged and none of these could be secured; by mid-afternoon it was evident that the attack had failed.{{sfn|Phillips|2004|pp=221–257}}

The Latin clergy discussed the situation amongst themselves and settled upon the message they wished to spread through the demoralised army. They had to convince the men that the events of 9 April were not God's judgment on a sinful enterprise: the campaign, they argued, was righteous and with proper belief it would succeed. The concept of God testing the determination of the crusaders through temporary setbacks was a familiar means for the clergy to explain failure in the course of a campaign. The clergy's message was designed to reassure and encourage the Crusaders. Their argument that the attack on Constantinople was spiritual revolved around two themes. First, the Greeks were traitors and murderers since they had killed their rightful lord, Alexios IV. The churchmen used inflammatory language and claimed that "the Greeks were worse than the Jews",{{sfn|Phillips|2004|pp=221–257}} and they invoked the authority of God and the pope to take action.

Although Innocent III had again demanded that they not attack, the papal letter was suppressed by the clergy, and the crusaders prepared for their own attack, while the Venetians attacked from the sea. Alexios V's army stayed in the city to fight, but when the unpaid Varangians left the city, Alexios V himself fled during the night. An attempt was made to find a further replacement emperor from amongst the Byzantine Greek nobility, but the situation had now become too chaotic for either of the two candidates who came forward to find sufficient support.{{citation needed|date=April 2021}}

On 12 April 1204, the weather conditions finally favoured the crusaders. A strong northern wind aided the Venetian ships in coming close to the walls and after a short battle approximately seventy crusaders managed to enter the city. Some were able to knock holes in the walls, large enough for only a few knights at a time to crawl through; the Venetians were also successful at scaling the walls from the sea, though there was fighting with the Byzantine infantry. The remaining Anglo-Saxon "axe bearers" had been amongst the most effective of the city's defenders, but they now attempted to negotiate higher wages from their Byzantine employers, before dispersing or surrendering.{{sfn|Nicolle|2011|p=77}} The crusaders captured the [[Blachernae]] section of the city in the northwest and used it as a base to attack the rest of the city. While attempting to defend themselves with a wall of fire, however, they burned even more of the city. This second fire left 15,000 people homeless.{{sfn|Phillips|2004|p=209}} The crusaders completely took the city on 13 April.

=== Sack of Constantinople ===
{{Main|Sack of Constantinople}}
[[File:Eugène Ferdinand Victor Delacroix 012.jpg|thumb|upright=1.15|''The Entry of the Crusaders into Constantinople'' ([[Eugène Delacroix]], 1840). The most infamous action of the Fourth Crusade was the sack of the Orthodox Christian city of [[Constantinople]].]]
The crusaders sacked Constantinople for three days, during which many ancient and medieval Greco-Roman works of art were stolen or ruined. Many of the civilian population of the city were killed and their property looted. Despite the threat of excommunication, the crusaders destroyed, defiled and looted the city's churches and monasteries.<ref name="Speros" /><ref name="Hughes" /> It was said that the total amount looted from Constantinople was about 900,000 silver marks. The Venetians received 150,000 silver marks that were their due, while the crusaders received 50,000 silver marks. A further 100,000 silver marks were divided evenly up between the crusaders and Venetians. The remaining 500,000 silver marks were secretly kept back by many crusader knights.<ref name="Ang">Konstam, ''Historical Atlas of The Crusades'', p. 162</ref><ref name="Tread663">W. Treadgold, ''A History of Byzantine State and Society'', p. 663</ref> The eyewitness accounts of [[Niketas Choniates]], [[Geoffrey of Villehardouin]], [[Robert of Clari]], and the anonymous Latin author of the ''[[Devastatio Constantinopolitana]]'' all accuse the crusaders of egregious rapacity.<ref name=":1" />

[[Speros Vryonis]] in ''Byzantium and Europe'' gives a vivid account of the sack:

{{blockquote|The Latin soldiery subjected the greatest city in Europe to an indescribable sack. For three days they murdered, raped, looted and destroyed on a scale which even the ancient Vandals and Goths would have found unbelievable. Constantinople had become a veritable museum of ancient and Byzantine art, an emporium of such incredible wealth that the Latins were astounded at the riches they found. Though the Venetians had an appreciation for the art which they discovered (they were themselves semi-Byzantines) and saved much of it, the French and others destroyed indiscriminately, halting to refresh themselves with wine, violation of nuns, and murder of Orthodox clerics. The Crusaders vented their hatred for the Greeks most spectacularly in the desecration of the greatest Church in Christendom. They smashed the silver iconostasis, the icons and the holy books of [[Hagia Sophia]], and seated upon the patriarchal throne a whore who sang coarse songs as they drank wine from the Church's holy vessels. The estrangement of East and West, which had proceeded over the centuries, culminated in the horrible massacre that accompanied the conquest of Constantinople. The Greeks were convinced that even the Turks, had they taken the city, would not have been as cruel as the Latin Christians. The defeat of Byzantium, already in a state of decline, accelerated political degeneration so that the Byzantines eventually became easy prey to the Turks. The Fourth Crusade and the crusading movement generally thus resulted, ultimately, in the victory of Islam, a result which was of course the exact opposite of its original intention.<ref name="Speros">{{cite book |last=Vryonis |first=Speros |author-link=Speros Vryonis |title=Byzantium and Europe |url=https://archive.org/details/byzantiumeurope00vryo |url-access=registration |publisher=Harcourt, Brace & World |location=New York |year=1967 |page=[https://archive.org/details/byzantiumeurope00vryo/page/152 152]}}</ref>}}

When Innocent III heard of the conduct of his pilgrims he was filled with shame and rage, and he strongly rebuked them.

== Holy Land ==
The main army that sailed from Venice to Constantinople experienced several waves of defections as men sought to fulfill their vows independently of the leadership. Most of them sailed directly from ports in [[Apulia]] (southern Italy) to Acre. According to Villehardouin, the majority of those who set out on the Fourth Crusade went to the Holy Land, while only a minority participated in the attack on Constantinople. Villehardouin, however, regarded those who went to the Holy Land as deserters of the main army and its leadership and he may have exaggerated their number in order to magnify the accomplishments of the minority that besieged Constantinople.<ref name=Kedar />{{sfn|Queller|Compton|Campbell|1974}}

Modern historians have tended to disregard Villehardouin's claims. [[Steven Runciman]] thought that only a "tiny proportion" and [[Joshua Prawer]] only some "pitiful remnants" of the original army arrived in the Holy Land. Recent studies suggest that the number was substantial but shy of a majority. Of the 92 named individuals who took the crusader vow in Villehardouin's account, between 23 and 26 of them went to the Holy Land. The rate of "desertion" seems highest among the French faction.{{sfn|Queller|Compton|Campbell|1974}} Only about a tenth of the knights who had taken the cross in Flanders arrived to reinforce the remaining Christian states in the Holy Land, but over half of those from the Île-de-France did. All told, about 300 knights with their retinues from northern France made it to the Holy Land.{{sfn|Nicolle|2011|p=78}} Of the contingents from Burgundy, Occitania, Italy and Germany there is less information, but there were certainly defections among the Occitan and German contingents.<ref name=Kedar />

A large sum of money raised by the preacher Fulk of Neuilly did reach the Holy Land. Before his death in May 1202, Fulk gave the money to the [[Abbey of Cîteaux]]. Abbot [[Arnaud Amalric]] sent it to Acre in two installments. It was used to repair walls, towers and other defences that had been damaged by the [[1202 Syria earthquake|earthquake of May 1202]]. A second wall was even added at Acre sometime before 1212.<ref name=Kedar />

=== Apulia to Acre ===
Several crusaders, instead of going on to Venice, turned south at [[Piacenza]] in the summer of 1202 intending to go directly to the Holy Land from ports in southern Italy. Among them were [[Vilain of Nully]], [[Henry of Arzillières]], [[Renard II of Dampierre-en-Astenois|Renard II of Dampierre]], [[Henry of Longchamp]] and Giles of Trasignies with their retinues. They do not seem to have been acting in concert or travelling together. Ultimately, several hundred knights and accompanying infantry reached the Holy Land via south Italian ports. The force was so small that King [[Aimery of Jerusalem]] refused to break his truce with the [[Ayyubids]] to allow them to go to war, despite the pleas of Renard, who was fulfilling the crusading vow of the late Count [[Theobald III of Champagne]] and possessed ample funds. As a result, eighty crusaders under Renard decided to go to the [[Principality of Antioch]], which had no such truce. Advised against such a move, they were ambushed on the road and all but Renard were killed or captured. Renard remained in captivity for thirty years.{{sfn|Queller|Compton|Campbell|1974}}

When the crusade was diverted to Zara, many crusaders returned home or else remained behind in Italy. Some bypassed the Venetian fleet and found other means of going to the [[Holy Land]]. [[Geoffrey I of Villehardouin|Geoffrey of Villehardouin]], the historian's nephew, was one of them. [[Stephen du Perche (died 1205)|Stephen of the Perche]], was prevented from going with the main army on account of illness. Upon his recovery in March 1203, he took ship in southern Italy and travelled directly to the Holy Land with many others who had remained behind, including Rotrou de Montfort and Yves of La Jaille. Stephen re-joined the main army after the fall of Constantinople.{{sfn|Queller|Compton|Campbell|1974}}

Following the siege of Zara, more contingents abandoned the main army. The crusaders sent [[Robert I of Fouencamps|Robert of Boves]] as an envoy to the pope, but after his mission was done he went straight to the Holy Land. Abbot Martin of Pairis joined him on the trip to Rome and afterwards took ship for Palestine at [[Siponto]]. Martin arrived in Acre on 25 April 1203 in the midst of an outbreak of plague. According to the ''[[Devastatio Constantinopolitana]]'', after the decision was made at Zara to place Alexios IV on the throne of Constantinople, the leaders of the crusade granted permission for about 1,000 men to leave and find their own way to the Holy Land. In fact, about 2,000 men abandoned the main army at that stage. Most of them were among the poorer crusaders, and two ships carrying them sank with loss of life. The German crusader Garnier of Borland also abandoned the main army after Zara.{{sfn|Queller|Compton|Campbell|1974}}

From Zara, an official embassy, led by [[Renaud of Montmirail]], was dispatched to the Holy Land. It included Hervé of Châtel, [[Guillaume de Ferrières|William III of Ferrières]], Geoffrey of Beaumont and the brothers John and Peter of Frouville. They were supposed to return to the main army within fifteen days of accomplishing their mission. In fact, they remained in the Holy Land and did not return until after the fall of Constantinople.{{sfn|Queller|Compton|Campbell|1974}}

In the winter of 1203–1204, [[Simon de Montfort, 5th Earl of Leicester|Simon de Montfort]] led a large contingent of defectors disgusted with the attack on Zara and opposed to the Constantinople venture. He and his men had even avoided the ruins of Zara and camped in Hungary.<ref name="Lippiatt 2012">{{citation |author=G. E. M. Lippiatt |title=Duty and Desertion: Simon of Montfort and the Fourth Crusade |journal=Leidschrift |volume=27 |issue=3 |year=2012 |pages=75–88 |url=https://openaccess.leidenuniv.nl/bitstream/handle/1887/72758/27-03-08_Lippiatt_printklaar.pdf}}.</ref> Among Simon's followers were his brother, [[Guy de Montfort, Lord of Sidon|Guy de Montfort]]; the [[Yvelines|Yvelinois]] Simon V of Neauphle, Robert IV Mauvoisin and Dreux II of Cressonsacq; Abbot [[Guy of Vaux-de-Cernay]]; and the unnamed abbot of [[Cercanceaux Abbey|Cercanceaux]]. Shortly afterwards they were joined by [[Enguerrand II of Boves]].{{sfn|Queller|Compton|Campbell|1974}}<ref name="Lippiatt 2017">{{citation |first=G. E. M. |last=Lippiatt |title=Simon V of Montfort and Baronial Government, 1195–1218 |publisher=Oxford University Press |year=2017}}.</ref> They marched up the coast from Zara back to Italy and then down the Italian coast, where they embarked for Palestine.{{sfn|Queller|Compton|Campbell|1974}}

=== Flemish fleet ===
For reasons unknown, Baldwin of Flanders divided his forces, leading half to Venice himself and sending the other half by sea. The Flemish fleet left Flanders in the summer of 1202 under the command of [[John II of Nesle]], [[Thierry of Flanders (flourished 1197–1207)|Thierry of Flanders]] and [[Nicholas of Mailly]].{{efn|Nicholas of Mailly joined the main army after the fall of Constantinople.{{sfn|Queller|Compton|Campbell|1974}}}} It sailed into the Mediterranean and, according to the chronicler [[Ernoul]], attacked and captured an unnamed Muslim city on the African coast. The city was left in the hands of the [[Livonian Brothers of the Sword]] and the fleet went on to [[Marseille]], where it wintered in 1202–1203. There the fleet was joined by a number of French crusaders, including Bishop [[Walter II (bishop of Autun)|Walter II of Autun]], Count [[Guigues III of Forez]], [[Bernard IV of Moreuil]], Henry of Arraines, Hugh of Chaumont, John of Villers, Peter Bromont and the brothers Walter and Hugh of Saint-Denis and their retinues.{{sfn|Queller|Compton|Campbell|1974}}

The pilots of Marseille had more experience sailing out of sight of land than those of any other Mediterranean port, having been doing it since the mid-12th century. In summer, they could make the trip to Acre in fifteen days. They possessed a fleet sufficient to transport the army of [[Richard the Lionheart]] on the [[Third Crusade]] in 1190. It was also a cheaper and more accessible port for the French contingent.{{sfn|Queller|Compton|Campbell|1974}}

Baldwin sent orders to his fleet in Marseille to sail at the end of March 1203 and rendezvous with the Venetian fleet off [[Methoni, Messenia|Methoni]].{{efn|Baldwin of Flanders' wife, [[Marie of Champagne]], sailed from Marseille to Acre in the spring of 1204. She was there when she learned of his election as emperor.{{sfn|Queller|Compton|Campbell|1974}}}} His messengers must also have brought news of the decision to go to Constantinople before proceeding to the Holy Land. For this reason the Flemish leaders may have opted to ignore the rendezvous and sail directly to Acre. It is also possible that they kept the rendezvous, but not finding the Venetian fleet (which did not get to Methoni before May) went on to Acre alone. They probably arrived there before Martin of Pairis on 25 April 1203.{{sfn|Queller|Compton|Campbell|1974}} At least a part of the fleet stopped at [[Kingdom of Cyprus|Cyprus]], where Thierry of Flanders made a claim on the island in the name of his wife, the [[Damsel of Cyprus]], daughter of [[Isaac Doukas Komnenos]], former emperor of Cyprus. Thierry, his wife and those knights that had supported him were ordered by Aimery to leave his kingdom, so they went to the [[Armenian Kingdom of Cilicia|Kingdom of Armenia]], homeland of Thierry's mother-in-law.<ref name="WHRdC">W. H. Rudt de Collenberg (1968), "L'empereur Isaac de Chypre et sa fille (1155–1207)", ''Byzantion'' '''38''' (1): 123–179, at 172–173.</ref>

The Flemish crusaders in Acre encountered the same difficulty as Renard of Dampierre. King Aimery was unwilling to break his truce for the sake of such a small army. The crusaders, therefore, split up. Some entered the service of the Principality of Antioch and others that of the [[County of Tripoli]]. Bernard of Moreuil and John of Villers joined Renard of Dampierre and were captured along with him. John of Nesle went to the aid of Armenia and thus found himself fighting some of his former comrades, since [[War of the Antiochene Succession|Armenia and Antioch were then at war]]. Sometime before 5 November 1203, however, the truce was broken. The Muslims seized two Christian ships and in retaliation, the Christians had seized six Muslim ships. The Flemish crusaders returned to the Kingdom of Jerusalem to fight.{{sfn|Queller|Compton|Campbell|1974}}

On 8 November, Martin of Pairis and [[Conrad of Swartzenberg]] were sent to the main army, then besieging Constantinople, to press for it to continue on to the Holy Land now that the truce was broken. The envoys arrived on 1 January 1204, but the army was in the midst of heavy fighting and nothing came of their embassy.{{sfn|Queller|Compton|Campbell|1974}}

Assessing the disastrous results of the expedition he had started, [[Pope Innocent III]] spoke against the crusaders thus:
{{blockquote|How, indeed, will the church of the Greeks, no matter how severely she is beset with affIictions and persecutions, return into ecclesiastical union and to a devotion for the Apostolic See, when she has seen in the Latins only an example of perdition and the works of darkness, so that she now, and with reason, detests the Latins more than dogs? As for those who were supposed to be seeking the ends of Jesus Christ, not their own ends, who made their swords, which they were supposed to use against the pagans, drip with Christian blood, they have spared neither religion, nor age, nor sex. They have committed incest, adultery, and fornication before the eyes of men. They have exposed both matrons and virgins, even those dedicated to God, to the sordid lusts of boys. Not satisfied with breaking open the imperial treasury and plundering the goods of princes and lesser men, they also laid their hands on the treasures of the churches and, what is more serious, on their very possessions. They have even ripped silver plates from the altars and have hacked them to pieces among themselves. They violated the holy places and have carried off crosses and relics.<ref>Pope Innocent III, ''Letters'', 126 (given July 12, 1205, and addressed to the papal legate, who had absolved the crusaders from their pilgrimage vows). Text is taken from the [http://www.fordham.edu/halsall/source/1204innocent.html Internet Medieval Sourcebook] by Paul Halsall. Modified. Original translation by J. Brundage.</ref>}}

== <span class="anchor" id="Aftermath"></span>Aftermath: partition of the Byzantine Empire ==
[[File:LatinEmpire2.png|thumb|upright=1.35|Partition of the Byzantine Empire into The [[Latin Empire]] and its Crusader Vassals, [[Empire of Nicaea]], [[Trapezuntine Empire]], and [[Despotate of Epirus]] after 1204{{icn|date=December 2024}}]]
The Byzantine Empire was apportioned between Venice and the leaders of the Crusade according to a [[Partitio terrarum imperii Romaniae|treaty]]; establishing the [[Latin Empire]] based in Constantinople. Boniface was not elected as the new emperor, although the citizens seemed to consider him as such; the Venetians thought he had too many connections with the former empire because of his brother, [[Renier of Montferrat]], who had been married to [[Maria Komnene (daughter of Manuel I)|Maria Komnene]], empress in the 1170s and 1180s and also because they thought that Boniface would favor the Genoese more than the Venetians as Montferrat was on Genoa's northern border. Instead, they placed [[Baldwin IX of Flanders|Baldwin of Flanders]] on the throne. Boniface went on to found the [[Kingdom of Thessalonica]], a vassal state of the new Latin Empire. The Venetians also founded the [[Duchy of the Archipelago]] in the Aegean Sea. Meanwhile, Byzantine refugees founded their own [[rump state]]s, the most notable of these being the [[Empire of Nicaea]] under [[Theodore I Laskaris|Theodore Laskaris]] (a relative of Alexios III), the [[Empire of Trebizond]], and the [[Despotate of Epirus]]. This was known as the [[Partitio terrarum imperii Romaniae]] in Latin.{{citation needed|date=April 2022}}

=== Venetian colonies ===
The [[Republic of Venice]] accumulated several possessions in Greece, which formed part of its ''[[Stato da Màr]]''. Some of them survived until the [[Fall of the Republic of Venice|fall of the Republic]] itself in 1797:
* [[Kingdom of Candia|Crete]], also known as Candia, (1211–1669),<ref name="maltezou105">Maltezou, ''Crete during the Period of Venetian Rule'', p. 105</ref> one of the Republic's most important overseas possessions, despite frequent revolts by the Greek population, it was retained until captured by the Ottomans in the [[Cretan War (1645–1669)|Cretan War]].<ref name="maltezou157">Maltezou, ''Crete during the Period of Venetian Rule'', p. 157</ref>
* [[Corfu]] (1207–1214 and 1386–1797), was captured by Venice from its Genoese ruler shortly after the Fourth Crusade. The island was soon retaken by the [[Despotate of Epirus]], but captured in 1258 by the [[Kingdom of Sicily]]. The island remained under Angevin rule until 1386, when Venice reimposed its control, which would last until the end of the Republic itself.
* [[Lefkas]] (1684–1797), originally part of the Palatine county and the Orsini-ruled Despotate of Epirus, it came under Ottoman rule in 1479, and was conquered by the Venetians in 1684, during the [[Morean War]].
* [[Zakynthos]] (1479–1797), originally part of the Palatine county and the Orsini-ruled Despotate of Epirus, it fell to Venice in 1479
* [[Cephalonia]] and [[Ithaca (island)|Ithaca]] (1500–1797), originally part of the Palatine county and the Orsini-ruled Despotate of Epirus, they came under Ottoman rule in 1479, and were [[Siege of the Castle of St. George|conquered]] by the Venetians in December 1500.{{sfn|Setton|1978|pp=98, 290, 522–523}}
* [[Tinos]] and [[Mykonos]], bequeathed to Venice in 1390,{{sfn|Miller|1908|p=365}} and lost to the Ottomans in 1715 and 1537 respectively.{{sfn|Miller|1908|p=654}}
* various coastal fortresses in the [[Peloponnese]] and mainland Greece:
** Modon ([[Methoni, Messenia|Methoni]]) and Coron ([[Koroni]]), occupied in 1207, confirmed by the [[Treaty of Sapienza]],{{sfn|Bon|1969|p=66}} and held until [[Ottoman–Venetian War (1499–1503)|taken]] by the Ottomans in August 1500.{{sfn|Setton|1978|pp=515–522}}
** [[Nauplia]] (Italian Napoli di Romania), acquired through the purchase of the lordship of [[Argos and Nauplia]] in 1388,{{sfn|Topping|1975|pp=153–155}} held until captured by the Ottomans in 1540.{{sfn|Fine|1994|p=568}}
** [[Argos, Peloponnese|Argos]], acquired through the purchase of the lordship of [[Argos and Nauplia]] but seized by the [[Despotate of the Morea]] and not handed over to Venice until June 1394,{{sfn|Topping|1975|pp=153–155}} held until captured by the Ottomans in 1462.{{sfn|Fine|1994|p=567}}
** [[Athens]], acquired in 1394 from the heirs of [[Nerio I Acciaioli]], but lost to the latter's bastard son [[Antonio I Acciaioli|Antonio]] in 1402–03, a fact recognized by the Republic in a treaty in 1405.{{sfn|Miller|1908|pp=354–362}}
** [[Parga]], port town on the coast of Epirus, acquired in 1401. It was governed as a dependency of Corfu, and remained so even after the end of the Venetian Republic in 1797, finally being ceded by the British to [[Ali Pasha of Ioannina|Ali Pasha]] in 1819.{{sfn|Miller|1908|p=365}}
** Lepanto ([[Naupaktos]]), port in [[Aetolia]], briefly seized by a Venetian captain in 1390, in 1394 its inhabitants offered to hand it over to Venice, but were rebuffed. Finally sold to Venice in 1407 by its Albanian ruler, [[Paul Spata]],{{sfn|Fine|1994|pp=356, 544}}{{sfn|Miller|1908|p=363}} lost to the Ottomans in 1540.{{sfn|Fine|1994|p=568}}
** [[Patras]], held in 1408–13 and 1417–19 in lease, for 1,000 ducats per year, from the [[Latin Archbishop of Patras]], who thus hoped to thwart a Turkish or Byzantine takeover of the city.{{sfn|Topping|1975|pp=161–163}}{{sfn|Miller|1908|pp=353–364}}
** The [[Northern Sporades]] ([[Skiathos]], [[Skopelos]], and [[Alonissos]]), were Byzantine possessions that came under Venetian rule after the Fall of Constantinople in 1453. They were captured by the Ottomans under [[Hayreddin Barbarossa]] in 1538.
** [[Monemvasia]] (Malvasia), a Byzantine outpost left unconquered by the Ottomans in 1460, it accepted Venetian rule, until captured by the Ottomans in 1540.{{sfn|Fine|1994|pp=567–568}}
** [[Vonitsa]] on the coast of Epirus, captured in 1684 and held as a mainland exclave of the Ionian Islands until the end of the Republic.
** [[Preveza]] on the coast of Epirus, occupied during the [[Morean War]] (1684–1699), recaptured in 1717 and held as a mainland exclave of the Ionian Islands until the end of the Republic.
* The whole of the Peloponnese or [[Morea]] peninsula was conquered during the [[Morean War]] in the 1680s and became a colony as the "[[Kingdom of the Morea]]", but it was [[Ottoman–Venetian War (1714–1718)|lost]] again to the Ottomans in 1715.

=== Genoese colonies ===
[[Republic of Genoa|Genoese]] attempts to occupy Corfu and Crete in the aftermath of the Fourth Crusade were thwarted by the Venetians. It was only during the 14th century, exploiting the terminal decline of the [[Byzantine Empire under the Palaiologos dynasty]], and often in agreement with the weakened Eastern Roman rulers, that various Genoese nobles established domains in the northeastern Aegean:
* The [[Gattilusi]] family established a number of fiefs, under nominal Eastern Roman suzerainty, over the island of [[Lesbos]] (1355–1462) and later the islands of [[Lemnos]], [[Thasos]] (1414–1462) and [[Samothrace]] (1355–1457), as well as the [[Thrace|Thracian]] town of [[Enez|Ainos]] (1376–1456).
* The [[Lordship of Chios]], consisting of the twin cities of New and Old [[Phocaea]], [[Samos]], [[Ikaria]], and [[Chios]] as its capital. From 1304 to 1329 under the [[Zaccaria]] family, and, after an Eastern Roman interlude, from 1346 and until the Ottoman conquest in 1566 under the ''[[Maona di Chio e di Focea]]'' company.

=== Crusader colonies ===
The [[Latin Empire]] and the 4th Crusade's leaders all created their own kingdoms in the [[Byzantine Empire]].

[[File:Greece in 1278.svg|thumb|right|upright=1.13|Map of the Greek and Latin states in southern Greece ca. 1278]]
* The [[Kingdom of Thessalonica]] (1205–1224), encompassing [[Macedonia (region)|Macedonia]] and [[Thessaly]]. This kingdom was given to the leader of the 4th Crusade, Boniface of Montferrat after he lost the election of Latin Emperor to Baldwin of Flanders. Boniface would expand Latin domains south, into southern Greece. After he was killed by Bulgarians, the kingdom was almost continuously troubled by warfare with the [[Second Bulgarian Empire]]; eventually, it was conquered by the [[Despotate of Epirus]] under [[Theodore Komnenos Doukas]]. Doukas would then replace the Kingdom of Thessalonica by the [[Empire of Thessalonica]].
* The [[Principality of Achaea]] (1205–1432/1454), encompassing the [[Morea]] or [[Peloponnese]] peninsula. It quickly emerged as the strongest state, and prospered even after the demise of the Latin Empire. Its main rival was the Byzantine [[Despotate of the Morea]], which eventually succeeded in conquering the Principality. It also exercised suzerainty over the Lordship of [[Argos and Nauplia]], and at one point or another, most of the other Latin states.
* The [[Duchy of Athens]] (1205–1458), with its two capitals [[Thebes, Greece|Thebes]] and Athens, and encompassing [[Attica]], [[Boeotia]], and parts of southern [[Thessaly]]. In 1311, the Duchy was [[Battle of Halmyros|conquered]] by the [[Catalan Company]], and in 1388, it passed into the hands of the [[Republic of Florence|Florentine]] Acciaiuoli family, which kept it until the Ottoman conquest in 1456.
* The [[Duchy of the Archipelago]] or of Naxos (1207–1579), founded by the [[Marco I Sanudo|Sanudo]] family, it encompassed most of the [[Cyclades]]. In 1383, it passed under the control of the Crispo family. The Duchy became an Ottoman vassal in 1537, and was finally annexed to the Ottoman Empire in 1579.
* [[Duchy of Philippopolis]] (1204 – after 1230), fief of the Latin Empire in northern Thrace, until its capture by the [[Second Bulgarian Empire|Bulgarians]].
* The [[Marquisate of Bodonitsa]] (1204–1414), like Salona, was originally created as a vassal state of the Kingdom of Thessalonica, but later came under the influence of Achaea. In 1335, the Venetian Giorgi family took control, and ruled until the Ottoman conquest in 1414.
* The [[County of Salona]] (1205–1410), centred at Salona (modern [[Amfissa]]), like Bodonitsa, was formed as a vassal state of the Kingdom of Thessalonica since King of Thessalonica, Boniface of Montferrat created the county. It would later come under the influence of Achaea. It then came under [[Catalan Company|Catalan]] and later Navarrese rule in the 14th century, before being sold to the [[Knights Hospitaller]] in 1403. It was finally conquered by the Ottomans in 1410.
* The [[County palatine of Cephalonia and Zakynthos]] (1185–1479). It encompassed the [[Ionian Islands]] of [[Cephalonia]], [[Zakynthos]], [[Ithaca (island)|Ithaca]], and, from around 1300, also [[Lefkas]] (Santa Maura). Created as a vassal to the [[Kingdom of Sicily]], it was ruled by the [[Orsini family]] from 1195 to 1335, and after a short interlude of [[County of Anjou|Anjou]] rule the county passed to the [[Tocco family]] in 1357. The county was split between Venice and the Ottomans in 1479.
* The [[Triarchy of Negroponte]] (1205–1470), encompassing the island of Negroponte ([[Euboea]]), originally a vassal of Thessalonica, then of Achaea. It was fragmented into three baronies (''terzi'' or "triarchies") run each by two barons (the ''sestieri''). This fragmentation enabled [[Republic of Venice|Venice]] to gain influence acting as mediators. By 1390 Venice had established direct control of the entire island, which remained in Venetian hands until 1470, when it was [[Ottoman–Venetian War (1463–79)|captured]] by the Ottomans.
* The [[Lordship of Argos and Nauplia]] (1212–1388) was made a lordship when after their conquest from the Byzantines in 1211–1212, the cities were granted as a fief to [[Otto de la Roche]], duke of Athens, by [[Geoffrey I of Villehardouin]], prince of Achaea. The lordship remained in the possession of the de la Roche and the Brienne dukes of Athens even after the conquest of the [[Duchy of Athens]] by the [[Catalan Company]] in 1311, and the Brienne line continued to be recognized as dukes of Athens there. In 1388 the two cities were sold to Venice but before Venice could take possession, Argos was seized by the Byzantine [[Despotate of Morea]] under [[Theodore I Palaiologos]], while his ally, while the Florentine Acciaiuoli family seized Nauplia. The Nauplia was soon captured by Venice, but Argos remained in Byzantine hands until 1394, when it too was handed over to Venice.
* [[Rhodes]] [[Hospitaller conquest of Rhodes|became]] the headquarters of the military monastic order of the [[Knights Hospitaller]] of Saint John in 1310, and the Knights retained control of the island (and neighbouring islands of the [[Dodecanese]] island group) until [[Siege of Rhodes (1522)|ousted by the Ottomans in 1522]].
* [[Lemnos]], an island known to Westerners as Stalimene formed a fief of the Latin Empire under the Venetian Navigajoso family from 1207 until conquered by the Byzantines in 1278. Its rulers bore the title of ''[[megadux]]'' ("grand duke") of the Latin Empire.

== Frankokratia ==
{{main|Frankokratia}}
The ''Frankokratia'' ({{langx|el|Φραγκοκρατία}}, {{langx|la|Francocratia}}, sometimes [[anglicized]] as ''Francocracy'', {{abbr|lit.|literally}} "rule of the [[Franks]]"), also known as ''Latinokratia'' ({{langx|el|Λατινοκρατία}}, {{langx|la|Latinocratia}}, "rule of the [[Latins (Middle Ages)|Latins]]") and, for the [[Republic of Venice|Venetian]] domains, ''Venetokratia'' or ''Enetokratia'' ({{langx|el|Βενετοκρατία or Ενετοκρατία}}, {{langx|la|Venetocratia}}, "rule of the Venetians"), was the period in [[Greek history]] after the Fourth Crusade when a number of primarily French and Italian states were established by the ''[[Partitio terrarum imperii Romaniae]]'' on the territory of the shattered [[Byzantine Empire]].

The terms ''Frankokratia'' and ''Latinokratia'' derive from the name given by the [[Eastern Orthodox Church|Orthodox]] Greeks to the [[Latin Church|Western]] French and Italians who originated from territories that once belonged to the [[Frankish Empire]], as this was the political entity that ruled much of the former [[Western Roman Empire]] after the collapse of Roman authority and power. The span of the ''Frankokratia'' period differs by region: the political situation proved highly volatile, as the Frankish states fragmented and changed hands, and the Greek successor states re-conquered many areas.

With the exception of the [[Ionian Islands]] and some islands or forts which [[Stato da Màr|remained in Venetian hands]] until the turn of the 19th century, the end of the ''Frankokratia'' in most Greek lands came with the [[Ottoman Greece|Ottoman conquest]], chiefly in the 14th to 17th centuries, which ushered in the period known as "''Tourkokratia''" ("rule of the Turks"; see [[Ottoman Greece]]). During the ensuing half-century, the unstable Latin Empire siphoned off much of Europe's crusading energy. The legacy of the Fourth Crusade was the deep sense of betrayal felt by the Greek Christians. With the events of 1204, the schism between the Churches in the East and West was not just complete but also solidified.<ref name="Encyclopædia Britannica 1983">p. 310, vol. 5; ''Encyclopædia Britannica'', 15th ed. 1983, {{ISBN|0-85229-400-X}}</ref>

During the ''Frankokratia'', the Latin Empire was faced with a number of enemies. After taking Constantinople the crusaders were not able to take possession of the entire empire. The Franks were faced by several Eastern Roman rump states, whose rulers considered themselves the legitimate successors to the Imperial throne. The three most important of these surviving Byzantine entities were the [[Despotate of Epirus]] in [[Epirus]], the [[Empire of Nicaea]] in [[Anatolia]], and the [[Empire of Trebizond]] in [[Paphlagonia]], [[Pontus (region)|Pontus]], [[Bithynia]], and [[Crimea]]. Besides the individual [[Rump state|Eastern Roman rump states]] in [[Epirus]], [[Empire of Nicaea|Nicaea]] and [[Empire of Trebizond|Trebizond]], the crusaders were threatened by the Christian [[Second Bulgarian Empire]] in [[Bulgaria]], [[Wallachia]], and the [[Balkans]] and the Muslim & nomadic [[Seljuk Sultanate of Rûm]] in Anatolia, and later the [[Mongol Empire]], or more specifically, the [[Golden Horde]]. Ultimately the crusaders lacked the numbers sufficient to permanently hold their new conquests.

The fragmented Eastern Roman rump states fought against the crusaders, Bulgarians, Turks, and each other.<ref>{{cite book |first=Jean |last=Richard |pages=252–257 |title=The Crusades c. 1071 – c. 1291 |date=1999 |publisher=Cambridge University Press |isbn=0-521-62369-3}}</ref> The unstable Latin Empire siphoned off much of Europe's crusading energy. The legacy of the Fourth Crusade and ''Frankokratia'' was also a deep sense of betrayal felt by the Greek Christians. With the events of 1204, the schism between the Churches in the East and West was not just complete but also solidified.<ref name="Encyclopædia Britannica 1983" />
During the ''Frankokratia'' various Latin–French lordships throughout Greece{{snd}}in particular, the [[Duchy of Athens]] and the [[principality of the Morea]]{{snd}}provided cultural contacts with western Europe and promoted the study of Greek. There was also a French cultural influence, notably the production of a collection of laws, the ''[[Assises de Romanie]]''. The ''[[Chronicle of Morea]]'' appeared in both [[French language|French]] and [[Greek language|Greek]] (and later Italian and Aragonese) versions. Impressive remains of Crusader castles and [[Gothic architecture|Gothic churches]] can still be seen in Greece. Nevertheless, the Latin Empire always rested on shaky foundations.

Constantinople was re-captured by the Nicaeans under [[Michael VIII Palaiologos]] in 1261, with naval support from the Genoese in the [[Reconquest of Constantinople]]. This led to the restoration of a diminished Byzantine Empire. Commerce with Venice was re-established but the Nicaeans gave their Genoese allies possession of Galata, a fortress on the northern banks of the Golden Horn.{{citation needed|date=April 2022}}

The Fourth Crusade had other and greater historical impacts. During the ''Frankokratia'' those Eastern Roman lands which were not under a stable government were permanently lost to the Seljuks in Anatolia. Southern Greece and the Greek islands remained mostly under rule of the crusaders, Italian nobles, and Venice. Even the [[Byzantine Greek]] [[Despotate of Epirus]] would also be ruled by another Italian noble family. Most of these crusader kingdoms would be annexed into the future [[Ottoman Empire]], not the resurgent Byzantine-Nicaean state. The treasury of the Byzantine Empire was depleted, most of it stolen by the crusaders. All of these factors would hasten the [[Fall of Constantinople|final fall of the Byzantine Empire]] to the [[Ottoman Turks]] in 1453 to the Ottoman Sultan, [[Mehmed II]]. This
final fall of the Eastern Roman Empire would usher in a new era to the ancient land of [[Greece]] which the Greeks would know as [[Tourkokratia]], or "the Rule of the Turks".

== Reactions to the Crusade ==
=== Contemporary opposition to the sack of Constantinople ===
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| source = [[Niketas Choniates]] laments the fall of Constantinople to the Crusaders.<ref>{{Cite book |first1=Niketas |last1=Choniates |first2=Harry J.  |last2=Magoulias |title=O City of Byzantium: Annals of Niketas Choniatēs |publisher=Wayne State University Press |year=1984 |isbn=978-0-8143-1764-8 |page=317 |url=https://books.google.com/books?id=O8arrZPM8moC}}</ref>
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Several prominent Crusaders, including [[Enguerrand II of Boves]], [[Simon de Montfort, 5th Earl of Leicester]] and [[Guy of Vaux-de-Cernay]], among others, disagreed with the attacks on Zara and Constantinople and refused to take part in them. Indeed, most of the Crusaders did not take part in the attacks in Constantinople or did so unwillingly.{{sfn|Queller|Compton|Campbell|1974}}

Byzantinist [[Jonathan Harris (historian)|Jonathan Harris]] wrote that when the decision was made to divert to Constantinople "A sizeable proportion [of Crusaders] left the army and made their own way to the Holy Land. Those who remained only agreed very reluctantly to the diversion when subjected to a mixture of financial and emotional blackmail. Even then, many hesitated before the final attack in April 1204, and had serious doubts as to whether it was legitimate to attack a Christian city in this way".<ref>{{Cite journal |last=Harris |first=Jonathan |date=2004 |title=The Debate on the Fourth Crusade |journal=History Compass |volume=2 |issue=1 |doi=10.1111/j.1478-0542.2004.00114.x |issn=1478-0542}}</ref>

The French nobleman [[Simon de Montfort, 5th Earl of Leicester|Simon de Montfort]], in particular, did not participate and was an outspoken critic. He and his associates, including Guy of Vaux-de-Cernay, left the crusade when the decision was taken to divert to [[Constantinople]] to place [[Alexius IV Angelus]] on the throne. Instead, Simon and his followers travelled to the court of [[King Emeric]] of Hungary and thence to [[Akko|Acre]].{{sfn|Phillips|2004|p=137}} Several other substantial contingents, including the large [[Flanders|Flemish]] fleet with [[Marie of Champagne]] on board, sailed directly to Acre as well.<ref name=":3">{{Cite book |last=Tyerman |first=Christopher |url=https://books.google.com/books?id=GIOVDwAAQBAJ |title=The World of the Crusades |date=2019 |publisher=Yale University Press |isbn=978-0-300-24545-5 |page=250}}</ref>

Monk and poet [[Guiot de Provins]] wrote a satirical play in response to the Crusade accusing the papacy of [[avarice]].<ref name=":2">{{Cite book |last=Throop |first=Palmer A. |url=http://archive.org/details/criticismofcrusa0000thro |title=Criticism of the Crusade: A Study of Public Opinion and Crusade Propaganda |date=1975 |publisher=Porcupine |isbn=978-0-87991-618-3 |page=30}}</ref> Somewhat later, [[Guilhem Figueira]] wrote a ''[[sirventes]]'' and repeated these accusations, asserting that greed was the primary factor behind the crusade. He harshly stated:<ref name=":2" />
{{Blockquote|text=Deceitful Rome, avarice ensnares you, so that you shear the wool of your sheep too much. May the Holy Ghost, who takes on human flesh, hear my prayer and break your beak, O Rome! You will never have a truce with me because you are false and perfidious with us and the Greeks ... Rome, you do little harm to the Saracens, but you massacre Greeks and Latins. In hell-fire and ruin you have your seat, Rome.|author=}}
However, [[Pope Innocent III]] also opposed the sack; he neither sanctioned it nor knew about it. Innocent III had forbidden the Crusaders to attack the Byzantine Empire, instructing the leader, Boniface of Montferrat, that "The crusade must not attack Christians, but should proceed as quickly as possible to the Holy Land".{{sfn|Queller|Madden|1997|p=38}} When he found out about the events he wrote two angry letters addressed to Boniface. One of them reads:<ref name=":1">{{Cite book |last=Perry |first=David M. |url=https://books.google.com/books?id=cJuYEAAAQBAJ&dq=SACRED+PLUNDER+T+VENICE+T+AND+THE+AFTERMATH+OF+THE+FOURTH+CRUSADE&pg=PP1 |title=Sacred Plunder: Venice and the Aftermath of the Fourth Crusade |date=2015 |publisher=Penn State Press |isbn=978-0-271-06681-3 |pages=14, 65, 69–71}}</ref>
{{Blockquote|text=How will the Greek Church... return to ecclesiastical unity and devotion to the Apostolic See, a church which has seen in the Latins nothing except an example of affliction and the works of Hell, so that now it rightly detests them more than dogs?... It was not enough for them [the Latins] to empty the imperial treasuries and to plunder the spoils of princes and lesser folk, but rather they extended their hands to church treasuries and, what was more serious, to their possessions, even ripping away silver tablets from altars and breaking them into pieces among themselves, violating sacristies and crosses, and carrying away relics.}}
Historian [[Robert Lee Wolff]] interprets the two letters from Innocent III as a sign of the Pope's "early spirit of understanding for the Greeks".<ref name=":1" />

Only one contemporary Arab-Muslim historian, [[Ibn al-Athir]], provided a detailed report of the sack of Constantinople by the Crusaders.<ref>{{Cite book |last1=Kedar |first1=Benjamin Z. |url=https://books.google.com/books?id=fFjUDAAAQBAJ&pg=PT92 |title=Crusades |volume=6 |last2=Phillips |first2=Jonathan |last3=Riley-Smith |first3=Jonathan |date=2016 |publisher=Routledge |isbn=978-1-351-98562-8}}</ref> It struck him as "an atrocity in its scale of rapine, slaughter and wanton destruction of centuries of classical and Christian civilisation".<ref name=":3" />

=== Modern assessment ===
The prominent medievalist [[Sir Steven Runciman]] wrote in 1954: "There was never a greater [[crime against humanity]] than the Fourth Crusade."<ref>{{cite book |author=Runciman |title=History of the Crusades |volume=3 |page=130}}</ref> According to historian Martin Arbagi, "The diversion of the Fourth Crusade in 1204 was one of the great atrocities of medieval history, and Pope Innocent III placed most of the blame on Venice".<ref>{{Cite journal |last=Arbagi |first=Martin |date=2007 |title=The Medieval Crusade. |url=https://go.gale.com/ps/i.do?p=AONE&sw=w&issn=00182370&v=2.1&it=r&id=GALE%7CA162576163&sid=googleScholar&linkaccess=abs |journal=The Historian |volume=69 |issue=1 |pages=166–168 |doi=10.1111/j.1540-6563.2007.00175_61.x |s2cid=145135119|url-access=subscription }}</ref> The controversy that has surrounded the Fourth Crusade has led to diverging opinions in academia on whether its objective was indeed the capture of Constantinople. The traditional position, which holds that this was the case, was challenged by Donald E. Queller and [[Thomas F. Madden]] in their book ''The Fourth Crusade'' (1997).{{sfn|Queller|Madden|1997}}

Constantinople was considered as a bastion of Christianity that defended Europe from Muslim invasion, and the Fourth Crusade's sack of the city dealt an irreparable blow to this eastern bulwark. Although the Greeks retook Constantinople after 57 years of Latin rule, the Crusade crippled the Byzantine Empire. Reduced to Constantinople, north-western Anatolia, and a portion of the southern Balkans, the empire fell when the Ottoman Muslims captured the city in 1453.<ref>{{cite book |last=Sherrard |first=Philip |title=Byzantium |publisher=Time-Life |year=1967 |pages=166–167}}</ref>

Eight hundred years later, [[Pope John Paul II]] twice expressed sorrow for the events of the Fourth Crusade. In 2001, he wrote to [[Archbishop Christodoulos of Athens|Christodoulos]], [[Archbishop of Athens]], "It is tragic that the assailants, who set out to secure free access for Christians to the Holy Land, turned against their brothers in the faith. The fact that they were Latin Christians fills Catholics with deep regret."<ref>{{cite web |url=http://www.ewtn.com/footsteps/words/CHRISTODOULOS_5_4.htm |title=In the Footsteps of St. Paul: Papal Visit to Greece, Syria & Malta – Words |website=EWTN |author=Pope John Paul II |date=2001 |access-date=2006-03-26 |archive-date=2009-12-04 |archive-url=https://web.archive.org/web/20091204015424/http://www.ewtn.com/footsteps/words/CHRISTODOULOS_5_4.htm }}</ref> In 2004, while [[Bartholomew I]], [[Patriarch of Constantinople]], was visiting the [[Apostolic Palace|Vatican]], John Paul II asked, "How can we not share, at a distance of eight centuries, the pain and disgust."<ref>{{cite news |url=https://news.bbc.co.uk/2/hi/europe/3850789.stm |title=Pope sorrow over Constantinople |work=[[BBC News]] |date=June 29, 2004}}</ref> This has been regarded as an apology to the Greek Orthodox Church for the massacres perpetrated by the warriors of the Fourth Crusade.{{sfn|Phillips|2004|p=xiii}}

In April 2004, in a speech on the 800th anniversary of the city's capture, Ecumenical Patriarch Bartholomew I formally accepted the apology. "The spirit of reconciliation is stronger than hatred," he said during a liturgy attended by Roman Catholic Archbishop [[Philippe Barbarin]] of Lyon, France. "We receive with gratitude and respect your cordial gesture for the tragic events of the Fourth Crusade. It is a fact that a crime was committed here in the city 800 years ago." Bartholomew said his acceptance came in the spirit of [[Easter]]. "The spirit of reconciliation of the resurrection... incites us toward reconciliation of our churches."<ref>{{cite web |url=http://www.incommunion.org/articles/issue-33/news-issue-33 |work=In Communion |title=News |issue=33 |author=Ecumenical Patriarch Bartholomew I |date=April 2004 |archive-url=https://web.archive.org/web/20071009183904/http://incommunion.org/articles/issue-33/news-issue-33 |archive-date=2007-10-09}}</ref>

The Fourth Crusade was one of the last of the major crusades to be launched by the Papacy, though it quickly fell out of Papal control. After bickering between laymen and the papal legate led to the collapse of the [[Fifth Crusade]], later crusades were directed by individual monarchs, mostly against Egypt. In one instance, the [[Sixth Crusade]] succeeded in restoring Jerusalem to Christian rule for 15 years.

== Gallery ==
<gallery class="center" widths=200 heights=160>
File:Bonfils, Félix (1831-1885) - Athens - Propylaia 1868-1875.jpg|The [[Frankish Tower (Acropolis of Athens)|Frankish tower]] on the [[Acropolis of Athens]], demolished in 1874
File:Castello Chlemoutsi.jpg|[[Chlemoutsi]] castle
File:Konrad von Grünenberg - Beschreibung der Reise von Konstanz nach Jerusalem - Blatt 20v-21r.jpg|[[Rhodes (city)]], around 1490
File:Rhodes old town Greece 6.jpg|[[Palace of the Grand Master of the Knights of Rhodes]]
File:Church of the Virgin of the Burgh 2010.jpg|Church of Virgin, [[Rhodes (city)]]
File:Fortress of Mytilini, Lesvos 2.jpg|Genoese [[Castle of Mytilene]]
File:GR-platamonas-festung.jpg|[[Platamon Castle]]
</gallery>

<gallery caption="Venetian possessions (till 1797)" widths=200 heights=160 class="center">
File:Venezianische Kolonien.png|[[Stato da Màr]] of the [[Republic of Venice]]
File:Venetiancrete.jpg|Map of the [[Kingdom of Candia]]
File:Negroponte by Giacomo Franco.jpg|Venetian map of Negroponte ([[Chalkis]])
File:Lepanto naupactus venecian fortress.JPG|Fortress of [[Nafpaktos]]
File:Old Fortress Contrafossa and Bridge.jpg|[[Old Fortress, Corfu]]
File:Palamidi castle - Agios Andreas Bastion.jpg|[[Palamidi]], [[Nafplion]]
File:Kreta - Iraklion - Alter Hafen2.jpg|[[Koules Fortress|Rocca a Mare]] fortress in [[Heraklion]]
File:File by Alexander Baranov - . (7366673008).jpg|The Morosini fountain, [[Lions Square]], [[Heraklion]]
</gallery>

== See also ==
* [[Bulgarian-Latin Wars]]
* [[Laskaris]]
* [[Latin Church in the Middle East]]
* [[Medieval Bulgarian Army]]
* [[Principality of Arbanon]]
* [[Second Bulgarian Empire]]
* [[Succession of the Roman Empire]]
* [[Third Crusade]]
* [[Timeline of Orthodoxy in Greece (1204–1453)]]

== Footnotes ==
{{notelist}}

== References ==
{{Reflist|30em}}

=== Primary sources ===
{{Refbegin}}
* {{cite web |author=[[Nicetas Choniates|Choniates, Nicetas]] |url=https://sourcebooks.fordham.edu/source/choniates1.asp |title=The Sack of Constantinople |website=Fordham.edu}}
* [[Chronicle of Morea]]
* {{cite web |author=[[Geoffrey de Villehardouin|de Villehardouin, Geoffrey]] |url=https://sourcebooks.fordham.edu/basis/villehardouin.asp |title=Chronicle of The Fourth Crusade and The Conquest of Constantinople |website=Fordham.edu}}
* {{cite web |author=[[Pope Innocent III]] |url=https://sourcebooks.fordham.edu/source/1204innocent.asp |title=Reprimand of Papal Legate |website=Fordham.edu}}
* {{cite web |author=[[Robert of Clari]] |url=http://www.deremilitari.org/resources/sources/clari.htm |title=The Conquest of Constantinople |website=deremilitari.org |access-date=2006-03-27 |archive-date=2006-06-23 |archive-url=https://web.archive.org/web/20060623063137/http://www.deremilitari.org/resources/sources/clari.htm }} (see also [https://sourcebooks.fordham.edu/source/clari1.asp excerpts] from another translation)
* {{cite web |url=https://sourcebooks.fordham.edu/sbook1k.asp#The%20Fourth%20Crusade |title=The Fourth Crusade 1204: Collected Sources |website=Fordham.edu}} (excerpts from several contemporary accounts)
* {{cite web |url=http://www.shsu.edu/~his_ncp/1204.html |title=The Sack of Constantinople by the Crusaders |date=1204 |website=shsu.edu |archive-url=https://web.archive.org/web/20070927230527/http://www.shsu.edu/~his_ncp/1204.html |archive-date=2007-09-27}}
* {{cite journal |url=https://www.academia.edu/31064036 |title=The Medieval Russian Account of the Fourth Crusade – A New Annotated Translation |website=academia.edu |last1=Savignac |first1=David}}
{{Refend}}

=== Secondary sources ===
{{Refbegin}}
* Angold, Michael, ''The Fourth Crusade'', Harlow: Pearson, 2003
* <!-- Bon, Antoine -->{{La Morée franque}}
* "Crusades". ''[[Encyclopædia Britannica]]'', 2006.
* <!-- Brand, Charles M. --> {{Byzantium Confronts the West}}
* <!-- Fine, John V. A. Jr. -->{{The Late Medieval Balkans}}
* Godfrey, John. ''1204: The Unholy Crusade''. Oxford University Press, 1980
* {{cite book |last=Harris |first=Jonathan |title=Byzantium and The Crusades |publisher=Bloomsbury |place=London |year=2014 |isbn=978-1-78093-767-0}}
* Harris, Jonathan, 'Collusion with the infidel as a pretext for military action against Byzantium', in ''Clash of Cultures: the Languages of Love and Hate'', ed. S. Lambert and H. Nicholson, Turnhout: Brepols, 2012, pp.&nbsp;99–117
* Hindley, Geoffrey. ''The Crusades: A History of Armed Pilgrimage and Holy War''. New York: Carroll and Graf Publishers, 2003. New ed.: ''The Crusades: Islam and Christianity in the Struggle for World Supremacy''. New York: Carroll and Graf Publishers, 2004.
* Lilie, Ralph-Johannes. ''Byzantium and the Crusader States, 1096–1204''. Translated by J. C. Morris and Jean E. Ridings. Oxford: Clarendon Press, 1993; originally published in 1988.
* [[Thomas F. Madden|Madden, Thomas F.]], and Donald E. Queller (1997). ''The Fourth Crusade: The Conquest of Constantinople''. Philadelphia: University of Pennsylvania Press
* {{Cite book |last=Madden |first=Thomas F. |year=2003 |title=Enrico Dandolo and the Rise of Venice |url=https://archive.org/details/enricodandoloris00madd |location=Baltimore, Md. |publisher=Johns Hopkins University Press |isbn=978-0-8018-7317-1}}
* [[Thomas F. Madden|Madden, Thomas F.]] (2004). ''Crusades: The Illustrated History''. London: Duncan Baird Pub.
* {{Cite book |last=Maltezou |first=Chrysa A. |script-chapter=el:Η Κρήτη στη Διάρκεια της Περίοδου της Βενετοκρατίας |trans-chapter=Crete during the Period of Venetian Rule (1211–1669) |pages=105–162 |editor-first=Nikolaos M. |editor-last=Panagiotakis |title=Crete, History and Civilization |volume=II |publisher=Vikelea Library, Association of Regional Associations of Regional Municipalities |year=1988 |language=el}}
* <!-- McNeal -->{{Setton-A History of the Crusades |last1=McNeal |first1=Edgar | last2=Wolff |first2=Robert Lee |volume=2 |chapter=The Fourth Crusade |pages=153–185 |chapter-url=http://digicoll.library.wisc.edu/cgi-bin/History/History-idx?type=article&did=History.CrusTwo.i0019&id=History.CrusTwo }}
* <!-- Miller, William -->{{Latins in the Levant}}
* <!-- Nicol, Donald M. (1988) -->{{Byzantium and Venice: A Study in Diplomatic and Cultural Relations}}
* {{Cite book |last=Nicolle |first=David |title=The Fourth Crusade 1202–04 |publisher=Osprey |place=Oxford |year=2011 |volume=237 |isbn=978-1-84908-319-5 |series=Osprey Campaign Series}}
* Noble, Peter S. [http://www.deremilitari.org/RESOURCES/PDFs/NOBLE.PDF Eyewitnesses of the Fourth Crusade&nbsp;– the War against Alexius III], ''Reading Medieval Studies'' v. 25, 1999.
* {{Cite book |last=Phillips |first=Jonathan P. |title=The Fourth Crusade and the Sack of Constantinople |publisher=Penguin |place=East Rutherford, NJ |date=2004 |isbn=978-0-14-303590-9}}
* Queller, Donald E., and Susan J. Stratton. "A Century of Controversy on the Fourth Crusade", in ''Studies in Medieval and Renaissance History'' v. 6 (1969): 237–277; reprinted in Donald E. Queller, ''Medieval Diplomacy and the Fourth Crusade''. London: Variorum Reprints, 1980.
* Queller, Donald E. ''The Latin Conquest of Constantinople''. John Wiley & Sons, 1971.
* {{Cite journal |last1=Queller |first1=Donald E. |last2=Compton |first2=Thomas K.n |last3=Campbell |first3=Donald A. |date=July 1974 |title=The Fourth Crusade: The Neglected Majority |journal=[[Speculum (journal)|Speculum]] |volume=49 |issue=3 |pages=441–465 |doi=10.2307/2851751 |jstor=2851751 |s2cid=163442765}}
* {{Cite book |last1=Queller |first1=Donald E. |url=https://books.google.com/books?id=0NpWFGvA5VQC |title=The Fourth Crusade: The Conquest of Constantinople |last2=Madden |first2=Thomas F. |last3=Andrea |first3=Alfred J. |date=1999 |publisher=University of Pennsylvania Press |isbn=978-0-8122-1713-1 |edition=2nd |orig-date=1997 |ref={{sfnref|Queller|Madden|1997}}}}
* <!-- Setton, Kenneth M. -->{{The Papacy and the Levant|volume=2}}
* <!-- Topping, Peter -->{{Setton-A History of the Crusades |last=Topping |first=Peter |chapter=The Morea, 1364–1460 |chapter-url=https://search.library.wisc.edu/digital/ALYOXG7V45YSNF9D/pages/AH5DXQFXBTGZ6P82 |volume=3 |pages=141–166}}
{{Refend}}

== Further reading ==
{{Refbegin}}
* Angold, Michael. ''The Fourth Crusade: Event and Context''. Harlow, NY: Longman, 2003.
* Bartlett, W. B. ''An Ungodly War: The Sack of Constantinople and the Fourth Crusade''. Stroud: Sutton Publishing, 2000.
* [[Ernle Bradford|Bradford, Ernle]]. ''The Great Betrayal: Constantinople, 1204''. London: Hodder & Stoughton, 1967.
* Harris, Jonathan, "The problem of supply and the sack of Constantinople", in ''The Fourth Crusade Revisited'', ed. Pierantonio Piatti, Vatican City: Libreria Editrice Vaticana, 2008, pp.&nbsp;145–154. {{ISBN|978-88-209-8063-4}}.
* Kazhdan, Alexander "Latins and Franks in Byzantium", in [[Angeliki E. Laiou]] and [[Roy Parviz Mottahedeh]] (eds.), ''The Crusades from the Perspective of Byzantium and the Muslim World''. Washington, D.C.: Dumbarton Oaks, 2001: 83–100.
* Kolbaba, Tia M. "Byzantine Perceptions of Latin Religious 'Errors': Themes and Changes from 850 to 1350", in Angeliki E. Laiou and Roy Parviz Mottahedeh (eds.), ''The Crusades from the Perspective of Byzantium and the Muslim World'' Washington, D.C.: Dumbarton Oaks, 2001: 117–143.
{{Refend}}

== External links ==
{{Spoken Wikipedia|FourthCrusade.ogg|date=2011-04-19}}
{{Commons category}}
* [http://www.byzantinemuseum.gr/en/permanentexhibition/byzantine_world/Franks_Latins_in_Byzantium/ Byzantine & Christian Museum / Franks and Latins in Byzantium]

{{Byzantine Empire topics|state=collapsed}}
{{Fragments of the Byzantine Empire}}
{{Authority control}}

{{Short description|Latin Christian armed expedition (1202–1204)}}

[[Category:Fourth Crusade| ]]
[[Category:1200s conflicts]]
[[Category:13th-century crusades]]
[[Category:1200s in the Byzantine Empire]]
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[[Category:East–West Schism]]
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[[Category:Principality of Achaea]]
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[[Category:Byzantine Empire–Holy See relations]]