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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 France, the United States, and most members of the British Commonwealth: Australia, Canada, 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 Dominions declined to sign: South Africa and the Irish Free State, the latter because it had no navy. Japan, a signatory of the First London Naval Treaty and already at war on the Asian mainland, withdrew from the conference on 15 January. Italy also declined to sign the treaty, largely as a result of the controversy over its 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 ships were restricted to a 35,000 long tons (35,562 t) standard displacement and 14-inch (356 mm) guns. 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.

Also submarines could not be larger than 2,000 tons or have any gun armament of greater than 5.1 inches, light cruisers were restricted to 8,000 tons and 6.1-inch (155 mm) or smaller guns and aircraft carriers 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 battleships, 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 classes of "treaty" battleships were built or laid down under its limitations, the King George V, North Carolina, and South Dakota 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 it was considered prudent to build vessels designed with 14-inch guns rather than find themselves without the new battleships, as redesigning the vessels and developing the proposed 15-inch guns would have delayed construction by 18 months. With the United States invoking the escalator clause after the keels were laid for the two members of the North Carolina class, they were completed with 16-inch guns (being planned from the onset to switch away from 14-inch guns with minor modification and short delay). The four battleships of the South Dakota class were designed with and protected against 16-inch guns, but maintained a 35,000 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 Iowa began in 1938 and its orders were placed in 1939; and carried 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" could not be sunk without the ships' crews and passengers being first delivered to "a place of safety" (for which lifeboats did not qualify, except under particular circumstances). The 1936 treaty confirmed Article 22 of the 1930 treaty remained in force, and "all others Powers to express their assent to the rules embodied in this Article". 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. It was this Protocol which was used at the post war Nuremberg Trial of Karl Dönitz for ordering unrestricted submarine warfare. These regulations did not prohibit arming merchantmen, but according to Dönitz, arming them, or having them report contact with submarines (or raiders), made them de facto naval auxiliaries and removed the protection of the cruiser rules. This made restrictions on submarines effectively moot.

See also

• Washington Naval Treaty, preceding treaty
• London Naval Treaty, preceding treaty
• Anglo-German Naval Agreement

Footnotes

1. O'Connell, D. P. (January 1957). "The Crown in the British Commonwealth". International and Comparative Law Quarterly. 6 (1): 115. doi:10.1093/iclqaj/6.1.103.
2. de Valera, Éamon (18 June 1936). "Committee on Finance; Vote 67—External Affairs". Dáil Éireann (8th Dáil) debates. Houses of the Oireachtas. Retrieved 15 July 2020. 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.
3. Treaty text. Article 4
4. Muir, "Gun Calibers and Battle Zones", 25
5. Holwitt, Joel I. "Execute Against Japan", PhD dissertation, Ohio State University, 2005, p. 93.
6. Holwitt, p.92: quoting Article 22 of the London Naval Treaty.
7. Treaty for the Limitation and Reduction of Naval Armaments, (Part IV, Art. 22, relating to submarine warfare). London, 22 April 1930
8. 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
9. Holwitt, pp. 94–95.
10. Holwitt, p. 6.
11. 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)
12. Holwitt, p. 6.

References

• Baker, A. D. III (1989). "Battlefleets and Diplomacy: Naval Disarmament Between the Two World Wars". Warship International. XXVI (3): 217–255. ISSN 0043-0374.
• Chessum, David (September 2020). "The 1936 London Naval Treaty". Warship International. LVII (3): 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. 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

• Full text of the Treaty

• Treaties of the United Kingdom
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• Arms control treaties
• History of the French Navy
• United States Navy in the 20th century
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• Treaties concluded in 1936
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