View source for Caltrop

{{short description|Area-denial weapon}}
{{for|the plant or its fruit|water caltrop|Tribulus terrestris}}
{{use dmy dates|cs1-dates=ly|date=June 2023}}
[[File:Roman caltrop.jpg|thumb|Roman caltrop at the Westphalian Museum of Archeology (German: Westfälisches Museum für Archäologie), [[Herne, North Rhine-Westphalia]], Germany]]
[[File:Löffelholz-Codex Ms-Berol-Germ-Qu-132 Fol 030v.png|thumb|Different types of caltrops and metal soles that can be buckled underneath as a countermeasure from Codex Löffelholz, Nuremberg, 1505]]

A '''caltrop''' (also known as '''caltrap''', '''galtrop''', '''cheval trap''', '''galthrap''',<ref>{{cite book|title=A Genealogical and Heraldic Dictionary of the Landed Gentry of Great Britain and Ireland | url=https://books.google.com/books?id=2FE4AQAAMAAJ&pg=PA672 |last= Burke| first= John| publisher = Henry Colburn | year = 1846 | page = 672 }}</ref> '''galtrap''', '''calthrop''', '''jackrock''' or '''crow's foot'''<ref>{{cite book|title=An Elementary Course of Military Engineering – Part I: Field Fortification, Military Mining and Siege Operations | url=https://books.google.com/books?id=7P1BAAAAYAAJ |last= Mahan| first= D.H.| publisher = John Wiley & Son | year = 1867 | page = 76 }}</ref><ref name = "Alesia-2006" >''[[Battle of Alesia]]'' ([[Julius Caesar|Caesar]]'s conquest of [[Gaul]] in 52 BC), Battlefield Detectives program, (2006), rebroadcast: 2008-09-08 on History Channel International (13:00-14:00 hrs EDST); Note: No mention of name caltrop at all, but illustrated and given as battle key to defend Roman lines of circumvallation per recent digs evidence.</ref>) is an [[area denial weapon]] made up of usually four, but possibly more, sharp nails or spines arranged in such a manner that one of them always points upward from a stable base (for example, a [[tetrahedron]]). Historically, caltrops were part of defences that served to slow the advance of troops, especially [[Cavalry|horse]]s, [[chariot]]s, and [[war elephant]]s, and were particularly effective against the soft feet of [[Camel cavalry|camel]]s.<ref>{{cite book|title=The Seven Great Monarchies Of The Ancient Eastern World, Vol 6. (of 7): Parthia| url=http://www.gutenberg.org/files/16166/16166-h/16166-h.htm#2HCH0023|last= Rawlinson| first= George}}</ref> In modern times, caltrops are effective when used against wheeled vehicles with pneumatic [[tire]]s.<ref name=HistoryNet>{{cite web |title=The Caltrop: A weapon that's barely changed over 2,300 years |author=Robert W. Reid |date=2006-09-01 |website=HistoryNet |url=https://www.historynet.com/weaponry-the-caltrop/#What%20Is%20A%20Caltrop? |access-date=2023-06-24 |quote=Today, it has reclaimed its old Greek name and reappeared as the tetrahedron, the bane of all vehicles running on pneumatic tires, and is used by both the military and police.}}</ref>

==Name==
The modern name "caltrop" is derived from the Old English {{lang|ang|calcatrippe}} (heel-trap),<ref>{{cite web |url=http://www.merriam-webster.com/dictionary/caltrop |title=Definition of Caltrop |website=www.merriam-webster.com |access-date=2 April 2018}}</ref><ref>{{cite web |url=https://www.dictionary.com/browse/caltrop |title=Definition of Caltrop |website=www.dictionary.com |access-date=21 March 2021}}</ref> such as in the French usage {{lang|fr|chausse-trape}} (shoe-trap). The Latin word {{lang|la|[[tribulus]]}} originally referred to this and provides part of the modern scientific name of a plant commonly called the caltrop, ''[[Tribulus terrestris]]'', whose spiked seed cases resemble caltrops and can injure feet and puncture bicycle tires. This plant can also be compared to ''[[Centaurea calcitrapa]]'', which is also sometimes referred to as the "caltrop". ''Trapa natans'', a water plant with similarly shaped spiked seeds and edible fruit, is called the "[[water caltrop]]".

==History==
[[File:Three Kingdoms Shu Bronze Caltrops (40512948263).jpg|thumb|Bronze caltrops from the [[Three Kingdoms]] era]]
[[File:Drevnosti RG v3 ill130c - Caltrop.jpg|right|thumb|A 16th-century caltrop]]
[[File:Imperial Encyclopaedia - Military Administration - pic553.svg|thumb|Illustration from the 18th-century Chinese book ''[[Gujin Tushu Jicheng]]'', showing caltrops with spikes that stick in the ground]]
The caltrop was called  {{lang|la|tribulus}}<ref>{{Cite encyclopedia |encyclopedia=[[A Latin Dictionary]] |title=trĭbŭlus |last1=Lewis |first1=Charlton T. |last2=Short |first2=Charles |date=1879}}</ref> by the ancient Romans, or sometimes {{lang|la|murex ferreus}},<ref>{{Cite encyclopedia |encyclopedia=[[A Latin Dictionary]] |title=mūrex |last1=Lewis |first1=Charlton T. |last2=Short |first2=Charles |date=1879}}</ref> the latter meaning "jagged iron" (literally "iron spiny snail-shell"). The former term derives from the ancient Greek word {{lang|grc-Latn|tribolos}} meaning three spikes.<ref>{{LSJ|tri/bolos|τρίβολος|ref}}</ref>

The late [[Ancient Rome|Roman]] writer [[Vegetius]], referring in his work ''[[De re militari]]'' to [[scythed chariot]]s, wrote:<ref>{{cite book| url=http://www.pvv.ntnu.no/~madsb/home/war/vegetius/dere07.php#21| title=The Military Institutions of the Romans Book III: Dispositions for Action| first=Flavius Vegetius| last=Renatus| year=390| chapter=Armed Chariots and Elephants| access-date=2005-10-22| archive-url=https://web.archive.org/web/20051224005323/http://www.pvv.ntnu.no/~madsb/home/war/vegetius/dere07.php#21#21| archive-date=2005-12-24| url-status=dead}}</ref>

{{blockquote|The armed [[chariot]]s used in war by Antiochus and Mithridates at first terrified the Romans, but they afterwards made a jest of them. As a chariot of this sort does not always meet with plain and level ground, the least obstruction stops it. And if one of the horses be either killed or wounded, it falls into the enemy's hands. The [[Roman legion|Roman soldiers]] rendered them useless chiefly by the following contrivance: at the instant the engagement began, they strewed the field of battle with caltrops, and the horses that drew the chariots, running full speed on them, were infallibly destroyed. A caltrop is a device composed of four spikes or points arranged so that in whatever manner it is thrown on the ground, it rests on three and presents the fourth upright.}}

Another example of the use of caltrops was found in [[Jamestown, Virginia]], in the United States:<ref>[http://www.americanheritage.com/articles/magazine/ah/1963/3/1963_3_66.shtml ''American Heritage'']. {{Webarchive|url= https://web.archive.org/web/20200806162058/https://www.americanheritage.com/digging-jamestown |date=2020-08-06 }}, March 1963.</ref>

{{blockquote|Undoubtedly the most unusual weapon or military device surviving from seventeenth-century Virginia is known as a caltrop, a single example of which has been found at Jamestown. It amounts to a widely spread iron tripod about three inches long with another leg sticking vertically upward, so that however you throw it down, one spike always sticks up. ... The fact that only one has been found would seem to suggest that they were used little, if at all. As with all military equipment designed for European wars, the caltrop's presence in Virginia must be considered in the light of possible attacks by the Spaniards as well as assaults from the Indians.}}

The Japanese version of the caltrop is called {{lang|ja-Latn|[[makibishi]]}}. Makibishi were sharp spiked objects that were used in feudal Japan to slow pursuers and also were used in the defence of samurai fortifications. Iron makibishi were called {{lang|ja-Latn|tetsubishi}}, while the makibishi made from the dried seed pod of the [[water caltrop]], or water chestnut (genus ''Trapa''), formed a natural type of makibashi called {{lang|ja-Latn|tennenbishi}}. Both types of makibishi could penetrate the thin soles of shoes, such as the {{lang|ja-Latn|[[waraji]]}} sandals, which were commonly worn in feudal Japan.<ref>{{cite book |url=https://books.google.com/books?id=U02pzwXNxBIC&pg=PA32 |title=Japanese Castles AD 250–1540 |first=Stephen |last=Turnbull |date=22 April 2008 |publisher=Bloomsbury USA |isbn=9781846032530 |access-date=2 April 2018 |via=Google Books}}</ref><ref>[https://books.google.com/books?id=eyMYelZlKekC&pg=PA119 ''Samurai, Warfare and the State in Early Medieval Japan''], [[Karl Friday]], Psychology Press, 2004 P. 119.</ref>

As a protective measure and countermeasure, European late medieval military engineers proposed iron soles that could be strapped under shoes like [[Patten (shoe)|pattens]] to protect the feet from hidden traps.<ref>{{Cite journal |author=Andreas Franzkowiak |title=issin sol behebet dir din füß gesunt – Eisensohlen gegen Fußangeln |journal=Experimentelle Archaeologie in Europa Jahrbuch 2025 |number=24 |publisher=European Association for the advancement of archaeology by experiment |location=Unteruhldingen |date=2025 |isbn=978-3-944255-24-8 |language=de |pages=61–73}}</ref>

<gallery mode=packed heights=160>
File:Weapons (1496876265).jpg|Traditional caltrops and mines from the [[Mongol Empire]]
</gallery>

==Modern uses==
[[File:Crows feet 2, Balaclava 1854.jpg|thumb|right|Crow's feet boards studded with spikes. These were laid on the ground to prevent the enemy from approaching the defences. This board was used by the Russian Army during the [[Battle of Balaclava]]. On display at Royal Engineers Museum, Kent.]]

===World War I===
{{citation needed span|date=June 2014|text=During service in [[World War I]], [[Australian Light Horse]] troops collected caltrops as keepsakes. These caltrops were either made by welding two pieces of wire together to form a four-pointed star or pouring molten steel into a mould to form a solid, seven-pointed star. The purpose of these devices was to disable horses. They were exchanged with French troops for bullets. The Australian Light Horse troops referred to them as "Horse Chestnuts".|reason=This claim from 2008 needs references to reliable sources.}}

===World War II===
Caltrops were used extensively and effectively during [[World War II]]. The modifications and variants produced by the [[Special Operations Executive]] (SOE) and the [[Office of Strategic Services]] (OSS) of the United States{{sfn|Lovell|1964|pp=42–43}} are still in use today within special forces and law enforcement bodies.{{who|date=January 2012}}

The Germans dropped ''crow's feet'' ({{langx|de|Krähenfüße}}).{{sfn|Civil Defence Training Pamphlet No 2|p=25}} These were made from two segments of sheet metal welded together into a tetrapod with four barbed points and then painted in camouflage colours. They came in two sizes with a side length of either {{convert|65|or|75|mm|in}}. They were dropped from aircraft in containers the same size as {{convert|500|kg|abbr=on}} bombs and were dispersed by a small explosive charge.{{sfn|Civil Defence Training Pamphlet No 2|p=25}}<ref>{{cite web
 | url        = http://www.lonesentry.com/articles/ttt08/german-spikes.html
 | title      = German Metal Spikes (Crowsfoot)
 | work       = Tactical and Technical Trends
 | date       = 5 November 1942
 | access-date = 30 April 2015
}}</ref>

===Tire deflation device===
{{See also|Spike strip}}
[[File:Caltrop.jpg|thumb|right|Caltrop used by the US [[Office of Strategic Services]]. The hollow spikes puncture self-sealing rubber tires. The hole in the center allows air to escape even if other ends of the tube are sealed by soft ground.]]
Inventors patented caltrop-like devices to deflate vehicle tires in a manner useful to law enforcement agencies or the military.<ref>
{{cite web
| url= http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=US2346713&F=0&QPN=US2346713
| title= Caltrop
| access-date=11 April 2008
| first= Walker
| last= Brooks
| date= 18 April 1944
| work= US2346713
| publisher= European Patent Office}}
</ref><ref>
{{cite web
| url = http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=US5921703&F=0
| title= Caltrop
| access-date=11 April 2008
| first= Jonathan
| last= Becker
| date= 13 July 1999
| work= US5921703
| publisher= European Patent Office|display-authors=etal}}
</ref> They are currently used by the military and police.<ref name=HistoryNet/>

===Labour disputes===
Caltrops have been used at times during [[labour strike]]s and other disputes. Such devices were used by some to destroy the tires of management and replacement workers.

Caltrops, referred to as "jack rocks" in news articles, were used during the [[Caterpillar Inc.|Caterpillar]] strike in 1995, puncturing tires on vehicles crossing the picket line in [[Peoria, Illinois]]. Because of their small size and the difficulty proving their source, both the company and the [[United Auto Workers]] blamed each other. Collateral damage included a school bus and a walking mail carrier.<ref>{{Cite news |url=http://www.nwitimes.com/uncategorized/spiky-jack-rocks-newest-weapon-in-cat-strike/article_497e117d-f0ae-5829-8ac8-0846bb8e136e.html |title=Spiky 'jack rocks' newest weapon in CAT strike |agency=Associated Press |newspaper=The New York Times|access-date=2017-01-11}}</ref> In [[Illinois]], the [[state legislature]] passed a law making the possession of such devices a [[misdemeanor]].<ref>{{ILCS|720|5|21-1.4 |title=Jackrocks violation |accessdate=21 October 2007}}{{Dead link|date=February 2024}}</ref>

=== Via drones ===
During the [[Russian invasion of Ukraine]], Ukraine has used drones to drop caltrops on key roads to disrupt wheeled vehicles carrying Russian military [[materiel]], and make them easier to target with [[loitering munition]]s.<ref>{{Cite web |last=Hambling |first=David |title=Ukraine Drops Ancient Roman Weapons From Drones To Stop Russian Trucks |url=https://www.forbes.com/sites/davidhambling/2024/04/12/ukraine-teams-ancient-and-modern-weapons-to-stop-russian-trucks/ |access-date=2024-04-13 |website=Forbes |language=en}}</ref>

==Symbol==

A caltrop has a variety of symbolic uses and is commonly found as a [[Charge (heraldry)|charge]] in [[heraldry]].<ref>{{cite web| url=http://www.burkes-peerage.net/articles/heraldry_c.aspx| work=Burkes Peerage and Gentry| title=A to Z Guide to Heraldic Terms| access-date=21 October 2007}}</ref> For instance, the Finnish noble family Fotangel ([[Swedish language|Swedish]] for 'caltrop') had arms ''gules'', three caltrops ''argent''.{{Citation needed|date=June 2023}}

It has also been adopted by military units: the caltrop is the symbol of the [[US Army's III Corps]], which is based at [[Fort Hood]], [[Texas]]. III Corps traces its lineage to the days of horse [[cavalry]], which used the caltrop as a defensive [[area denial weapon]].{{Citation needed|date=June 2023}}

The caltrop is also the symbol of the [[United States Marine Corps]]' [[3rd Marine Division (United States)|3rd Division]], formed on 16 September 1942.{{Citation needed|date=July 2018}}

<gallery mode=packed upright=160>
File:Coat of arms of Stirling.svg|Coat of arms of [[Stirling]]
File:3 Corps Shoulder Sleeve Insignia.svg|Shoulder insignia of [[III Corps (United States)]] 
File:3DMARDIV Vector Caltrap.png|[[3rd Marine Division (United States)]]
</gallery>

==Similar devices==
[[Image:Rozsochac.JPG|thumb|Czech hedgehogs deployed at the [[Stachelberg|Stachelberg fortress]] in Czechoslovakia in 1938]]
[[Punji stick]]s perform a similar role to caltrops. These are sharpened sticks placed vertically in the ground. Their use in modern times targets the body and limbs of a falling victim by means of a pit or tripwire.{{citation needed|date = December 2019}}

During the [[Second World War]], large caltrop-shaped objects made from [[reinforced concrete]] were used as [[anti-tank]] devices, although it seems that these were rare.<ref>{{cite web| url=http://www.britarch.ac.uk/projects/dob/crom1b.html| title=The 'Caltrop' as Anti-Tank Obstacle| publisher=British Archaeology| access-date=4 March 2006| archive-date=2005-12-20 | archive-url=https://web.archive.org/web/20051220132749/http://www.britarch.ac.uk/projects/dob/crom1b.html| url-status=dead}}</ref> Much more common were concrete devices called [[dragon's teeth (fortification)|dragon's teeth]], which were designed to wedge into [[tank]] treads. Large ones weighing over {{convert|1|tonne}} are still used defensively to deny access to wheeled vehicles, especially in camp areas. As dragon's teeth are immobile, the analogy with the caltrop is inexact. Another caltrop-like defence during World War II was the massive steel, freestanding [[Czech hedgehog]]; the works were designed as anti-tank obstacles and could also damage [[landing craft]] and [[warship]]s that came too close to shore. These were used by the Germans to defend beaches in [[Normandy Landings|Normandy]] and other coastal areas.<ref>{{Cite web|title=D-Day Beach Obstacles|url=https://www.d-daytoursnormandy.com/beach-obstacles-of-the-d-day-normandy-invasion/|access-date=January 1, 2021|website=D-Day Tours of Normandy|date=14 December 2019 }}</ref> [[Czech hedgehog]]s are heavily featured and plainly visible in the 1998 [[Steven Spielberg]]-directed American [[Epic film|epic]] [[war film]] ''[[Saving Private Ryan]]'', throughout the scenes early in the film depicting the June{{spaces}}6, 1944 [[Omaha Beach]] assault (part of the [[Normandy landings]] during [[World War II]]).

[[Tetrapod (structure)|Tetrapods]] are concrete blocks shaped like caltrops, which interlock when piled up. They are used as [[riprap]] in the construction of [[breakwaters]] and other sea defences, as they have been found to let the water pass through them and interrupt natural processes less than some other defenses.{{citation needed|date = December 2019}}

==See also==
{{Commons category|Caltrops (weapon)}}
* [[Booby trap]]
* [[Knucklebones]], a game, with similar hazards
* [[Triskelion]]

==Footnotes==
{{reflist|30em}}

==References==
* [https://web.archive.org/web/20070517095337/http://www.scotclans.com/clans/Drummond/history.html Clan Drummond], a brief history, at Scot Clans
* John L. Cotter and J. Paul Hudson, ''New Discoveries at Jamestown, Site of the First Successful English Settlement in America'', 1957 [http://www.gutenberg.org/files/16277/16277-h/16277-h.htm#caltrop Project Gutenberg]
* {{cite book
  | last       = Lovell
  | year       = 1964
  | first      = Stanley P
  | title      = Of spies & stratagems
  | url       = https://archive.org/details/ofspiesstratagem00love
  | url-access = registration
  | publisher  = Pocket Books
  | asin       = B0007ESKHE
 }}

;Official documents
* {{cite book
  | title      = Civil Defence Training Pamphlet No 2: Objects Dropped From the Air
  | author     = Ministry of Home Security
  | publisher  = His Majesty's Stationery Office
  | year       = 1944
  | ref        = {{harvid|Civil Defence Training Pamphlet No 2}}
 }}

{{Fortifications}}

[[Category:Roman weapons]]
[[Category:Roman fortifications]]
[[Category:Area denial weapons]]
[[Category:Engineering barrages]]
[[Category:Fortification (obstacles)]]
[[Category:Medieval weapons]]
[[Category:Guerrilla warfare tactics]]
[[Category:Metallic objects]]
[[Category:Tetrahedra]]