View source for Second London Naval Treaty

{{Short description|1936 international arms control treaty}}
{{Use British English|date=March 2012}}
{{Use dmy dates|date=August 2021}}
[[File:USS North Carolina Fit out NARA 1941-04-17.jpg|thumb|upright=1.2|The [[displacement (ship)|displacement]] of the ''[[North Carolina-class battleship|North Carolina]]'' (shown is the {{USS|North Carolina|BB-55|6}}) and ''[[South Dakota-class battleship (1939)|South Dakota]]''-classes were limited by the Second London Naval Treaty.]]

The '''Second London Naval Treaty''' was an [[international treaty]] signed as a result of the Second London Naval Disarmament Conference held in [[London]]. The conference started on 9 December 1935 and the treaty was signed by the participating nations on 25 March 1936.

==Treaty==
The signatories were [[French Third Republic|France]], the [[United States]], and the major constituents of the [[British Empire]]: [[Australia]], [[Canada]], [[British Raj|India]], [[New Zealand]], and the [[United Kingdom]] (on behalf of itself and "all parts of the British Empire which are not separate [[Members of the League of Nations]]"). Two Commonwealth [[Dominion]]s declined to sign: [[Union of South Africa|South Africa]] and the [[Irish Free State]],<ref>{{cite journal |last1=O'Connell |first1=D. P. |title=The Crown in the British Commonwealth |journal=International and Comparative Law Quarterly |date=January 1957 |volume=6 |issue=1 |page=115|doi=10.1093/iclqaj/6.1.103 }}</ref> the latter because [[Irish Naval Service#History|it had no navy]].<ref>{{cite web |last1=de Valera |first1=Éamon |title=Committee on Finance; Vote 67—External Affairs |url=https://www.oireachtas.ie/en/debates/debate/dail/1936-06-18/15/#para_129 |website=Dáil Éireann (8th Dáil) debates |publisher=Houses of the Oireachtas |access-date=15 July 2020 |language=en-ie |date=18 June 1936 |quote=At the opening meeting of the conference, the Saorstát delegate made it clear that Saorstát Eireann was participating in it because, by an article of the Treaty of 1930, all the signatories had undertaken to meet in conference before the Treaty of 1930 terminated— that is to say, before December of 1936. The Saorstát Government had made it clear that, in their view, the conference on naval limitations should be confined to naval powers, and that as Saorstát Eireann had no navy and was not working on a naval programme, there was no reason for its participation in the conference other than for the reasons stated. }}</ref> [[Empire of Japan|Japan]], a signatory of the [[London Naval Treaty|First London Naval Treaty]] and [[Second Sino-Japanese War#occupation|already at war]] on the Asian mainland, withdrew from the conference on 15 January. [[Kingdom of Italy|Italy]] also declined to sign the treaty, largely as a result of the controversy over its [[Second Italo-Ethiopian War|invasion of Abyssinia]] (Ethiopia); Italy was under sanctions from the [[League of Nations]].

The conference was intended to limit the growth in naval armaments until its expiration in 1942.  The absence of Japan (a very significant naval power) prevented agreement on a ceiling on the numbers of warships.  The treaty did limit the maximum size of the signatories' ships, and the maximum calibre of the guns which they could carry. First of all, [[capital ship]]s were restricted to a {{convert|35000|LT|t|0}} [[standard displacement]] and 14-inch (356&nbsp;mm) guns.<ref>Treaty text. Article 4</ref> However, a so-called "escalator clause" was included at the urging of American negotiators in case any of the countries that had signed the [[Washington Naval Treaty]] refused to adhere to this new limit. This provision allowed the signatory countries of the Second London Treaty—France, the United Kingdom and the United States—to raise the limit from 14-inch guns to 16-inch if Japan or Italy still refused to sign after 1 April 1937.<ref>Muir, "Gun Calibers and Battle Zones", 25</ref>

Also [[submarine]]s could not be larger than 2,000 tons or have any gun armament of greater than 5.1&nbsp;inches, light [[cruiser]]s were restricted to 8,000 tons and 6.1-inch (155&nbsp;mm) or smaller guns and [[aircraft carrier]]s were restricted to 23,000 tons. Article 25 however gave the right to depart limitations if any other country authorised, constructed or acquired a capital ship, an aircraft carrier, or a submarine exceeding treaty limits, and if such a departure would be necessary for national security. For this reason, in 1938 the treaty parties agreed on a new displacement limit of 45,000 tons for [[battleship]]s, the ill-fated [[battlecruiser]] already having fallen out of favor.

This London Naval Treaty effectively ended on 1 September 1939 with the beginning of World War II.  Even during its brief period of supposed effectiveness, three [[Ship class|class]]es of "treaty" battleships were built or laid down under its limitations, the ''[[King George V-class battleship (1939)|King George V]]'', {{sclass|North Carolina|battleship|5}}, and {{sclass|South Dakota|battleship (1939)|5}} classes. The designs of the ''King George V'' and ''North Carolina'' classes were initiated before the escalator clause was invoked, being intended to be armed with, and protected against, 14-inch guns. The United Kingdom declined to invoke the clause, as redesigning the vessels and developing the proposed 15-inch guns would have delayed construction by 18 months, and since these new battleships were badly needed it was considered prudent to build vessels already finalized with 14-inch guns, even if that meant accepting a reduction in firepower compared to adversaries. The United States invoked the escalator clause after the keels were laid for the two members of the ''North Carolina'' class, since the class was designed from the onset to be up-gunned from the original 14-inch main battery with minor modification, so they were completed with 16-inch guns since the United States could afford the delay. However, the completed vessel was an unbalanced battleship since its armor scheme was not proof against its up-gunned main armament, so no further ships of the ''North Carolina'' were ordered. The four battleships of the ''South Dakota'' class were designed with and protected against 16-inch guns, but maintained a 35,000&nbsp;ton standard displacement, so this necessitated a shorter hull which made for a compact and cramped ship. No longer limited to the Second London Naval Treaty but still constrained by the need to pass through the [[Panama Canal]], design of the {{sclass|Iowa|battleship|5}} began in 1938 and its orders were placed in 1939; with improved 16-inch guns and greater speed on a displacement of 45,000 tons.

Article 22 of the 1930 Treaty of London relating to submarine warfare declared [[international law]] (the so-called "[[cruiser rules]]") applied to submarines as well as to surface vessels. Also, unarmed merchant vessels which did not demonstrate "persistent refusal to stop...or active resistance to visit or search"<ref>Holwitt, Joel I. ''"Execute Against Japan"'', PhD dissertation, Ohio State University, 2005, p. 93.</ref> could not be sunk without the ships' crews and passengers being first delivered to "a place of safety" (for which [[Lifeboat (shipboard)|lifeboats]] did not qualify, except under particular circumstances).<ref>Holwitt, p.92: quoting Article 22 of the [[London Naval Treaty]].</ref> The 1936 treaty confirmed Article 22 of the 1930 treaty remained in force, and "all others Powers [were invited] to express their assent to the rules embodied in this Article".<ref>[http://www.icrc.org/ihl.nsf/FULL/310?OpenDocument Treaty for the Limitation and Reduction of Naval Armaments, (Part IV, Art. 22, relating to submarine warfare). London, 22 April 1930]</ref><ref>[http://www.icrc.org/ihl.nsf/INTRO/330?OpenDocument Procès-verbal relating to the Rules of Submarine Warfare set forth in Part IV of the Treaty of London of 22 April 1930. London, 6 November 1936]</ref> This became known as the London Submarine Protocol, and over thirty-five nations eventually did subscribe to it, including the U.S., Britain, Germany, and Japan.<ref>Holwitt, pp. 94–95.</ref> It was this Protocol which was used at the post war [[Nuremberg Trials|Nuremberg Trial]] of [[Karl Dönitz]] for ordering [[unrestricted submarine warfare]]. These regulations did not prohibit arming merchantmen,<ref>Holwitt, p. 6.</ref> but according to Dönitz, arming them, or having them report contact with submarines (or [[Commerce raiding|raider]]s), made them ''de facto'' naval auxiliaries and removed the protection of the cruiser rules.<ref>Dönitz, Karl. ''Memoirs: Ten Years and Twenty Days''; von der Poorten, Edward P. ''The German Navy in World War II'' (T. Y. Crowell, 1969); Milner, Marc. ''North Atlantic run : the Royal Canadian Navy and the battle for the convoys'' (Vanwell Publishing, 2006)</ref> This made restrictions on submarines effectively moot.<ref>Holwitt, p. 6.</ref>{{clarify|date=January 2020}}

==See also==
* [[Washington Naval Treaty]], preceding treaty
* [[London Naval Treaty]], preceding treaty
* [[Anglo-German Naval Agreement]]

==Footnotes==
{{reflist}}

== References ==
* {{cite journal|last1=Baker|first1=A. D. III|year=1989 |title=Battlefleets and Diplomacy: Naval Disarmament Between the Two World Wars|journal=Warship International|volume=XXVI |issue=3 |pages=217–255 |issn=0043-0374}}
*{{cite journal |last1=Chessum |first1=David|title=The 1936 London Naval Treaty |journal=Warship International |date=September 2020 |volume=LVII |issue=3 |pages=197–198 |issn=0043-0374}}
* Dönitz, Karl. ''Memoirs: Ten Years and Twenty Days''. 1952.
* Holwitt, Joel I. "Execute Against Japan", PhD dissertation, Ohio State University, 2005, p.&nbsp;93.
* Milner, Marc. ''North Atlantic run : the Royal Canadian Navy and the battle for the convoys''. St. Catharines, Ontario: Vanwell Publishing, 2006.
* Muir Jr., Malcolm. "Gun Calibers and Battle Zones: The United States Navy's Foremost Concern During the 1930s." ''Warship International'' no. 1 (1980): 24–35. {{issn|0043-0374}} {{oclc|1647131}}
* Von der Poorten, Edward P. ''The German Navy in World War II''. New York: T. Y. Crowell, 1969

==External links==
*[http://www.navweaps.com/index_tech/tech-089_London_Treaty_1936.htm Full text of the Treaty]

{{Interwar Naval Arms Limitation|state=expanded}}
{{Franklin D. Roosevelt}}
{{Authority control}} 

[[Category:Treaties of the United Kingdom]]
[[Category:Treaties of the United States]]
[[Category:Arms control treaties|London Naval Treaty, Second]]
[[Category:History of the French Navy]]
[[Category:United States Navy in the 20th century]]
[[Category:History of the Royal Navy]]
[[Category:1936 in France]]
[[Category:1936 in the United Kingdom]]
[[Category:1936 in the United States]]
[[Category:Treaties concluded in 1936]]
[[Category:Treaties of the French Third Republic]]
[[Category:Interwar-period treaties]]
[[Category:Naval treaties]]
[[Category:1936 in British politics]]
[[Category:1936 in military history]]