London Naval Treaty

Menu and List of Official Toasts at formal dinner which opened the London Naval Conference of 1930

The signing of the treaty remains inextricably intertwined with the ongoing negotiations, which began before the official start of the London Naval Conference of 1930, evolved throughout the progress of the official conference schedule, and continued for years afterward.

The treaty was seen as an extension of the conditions agreed in the Washington Naval Treaty, an effort to prevent a naval arms race after World War I.

The conference was a revival of the efforts that had gone into the 1927 Geneva Naval Conference at which the various negotiators had been unable to reach agreement because of bad feelings between the British and the American governments. The problem may have initially arisen from discussions held between US President President Herbert Hoover and UK Prime Minister Ramsay MacDonald at Rapidan Camp in 1929, but a range of factors affected tensions, which were exacerbated by the other nations at the conference.[3]

Under the treaty, the standard displacement of submarines was restricted to 2,000 tons, with each major power being allowed to keep three submarines of up to 2,800 tons except that France was allowed to keep one. The submarine gun caliber was also restricted for the first time to 6.1 in (155 mm) with one exception, an already-constructed French submarine being allowed to retain 8 in (203 mm) guns. That put an end to the 'big-gun' submarine concept pioneered by the British M class and the French Surcouf.

The treaty also established a distinction between cruisers armed with guns up to 6.1 in (155 mm) ("light cruisers" in unofficial parlance) from those with guns up to 8 in (203 mm) ("heavy cruisers"). The number of heavy cruisers was limited: Britain was permitted 15 with a total tonnage of 147,000, the Americans 18 totalling 180,000, and the Japanese 12 totalling 108,000 tons. For light cruisers, no numbers were specified but tonnage limits were 143,500 tons for the Americans, 192,200 tons for the British, and 100,450 tons for the Japanese.[4]

Destroyer tonnage was also limited, with destroyers being defined as ships of less than 1,850 tons and guns up to 5.1 in (130 mm). The Americans and the British were permitted up to 150,000 tons and Japan 105,500 tons.

Article 22 relating to submarine warfare declared international law applied to them as to surface vessels. Also, merchant vessels that demonstrated "persistent refusal to stop" or "active resistance" could be sunk without the ship's crew and passengers being first delivered to a "place of safety."[5]

Article 8 outlined smaller surface combatants. Ships between 600 and 2,000 tons, with guns not exceeding 6 in (152 mm) with a maximum of four gun mounts above 3 in (76 mm) without torpedo armament and up to 20 kn (37 km/h), were exempt from tonnage limitations. The maximum specifications were designed around the French Bougainville-class avisos, which were in construction at the time.

Warships under 600 tons were also completely exempt. That led to creative attempts to use the unlimited nature of the exemption with the Italian Spica-class torpedo boats, Japanese Chidori-class torpedo boats, French La Melpomène-class torpedo boats and British Kingfisher-class sloops.[6]

The next phase of attempted naval arms control was the Second Geneva Naval Conference in 1932. That year, Italy "retired" two battleships, twelve cruisers, 25 destroyers and 12 submarines; in all, 130,000 tons of naval vessels were scrapped or put into reserve.[7] Active negotiations among the other treaty signatories continued during the following years.[8]

That was followed by the Second London Naval Treaty of 1936.

• Treaty for the Limitation of Naval Armament
• Washington Naval Treaty
• Second London Naval Treaty – List of treaties signed in London.
• Treaty of London – List of treaties signed in London.
• May 15 Incident – attempted coup in Japan

• Baker, A. D., III (1989). "Battlefleets and Diplomacy: Naval Disarmament Between the Two World Wars". Warship International. XXVI (3): 217–255. ISSN 0043-0374.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• Dingman, Roger. Power in the Pacific: The Origins of Naval Arms Limitation, 1914–1922 (1976)
• Goldstein, Erik, and John H. Maurer, eds. The Washington Conference, 1921–22: Naval Rivalry, East Asian Stability and the Road to Pearl Harbor (Taylor & Francis, 1994).
• Maurer, John, and Christopher Bell, eds. At the Crossroads between Peace and War: The London Naval Conference in 1930 (Naval Institute Press, 2014).
• Redford, Duncan. "Collective Security and Internal Dissent: The Navy League's Attempts to Develop a New Policy towards British Naval Power between 1919 and the 1922 Washington Naval Treaty." History 96.321 (2011): 48-67.
• Roskill, Stephen. Naval Policy Between Wars. Volume I: The Period of Anglo-American Antagonism 1919–1929 (Seaforth Publishing, 2016).
• Steiner, Zara S. (2005). The Lights that Failed: European International History 1919–1933. Oxford: Oxford University Press. ISBN 978-0-19-822114-2; OCLC 58853793

• Text of the treaty