London Naval Treaty
The London Naval Treaty, established in 1930, emerged as a crucial agreement in the context of post-World War I naval disarmament efforts. Following the Washington Naval Treaty of 1922, which aimed to limit battleships and aircraft carriers, the London Treaty sought to further regulate destroyers, submarines, and cruisers among the United States, Great Britain, and Japan. The treaty set specific tonnage limits and armament specifications for these naval vessels, allowing the U.S. and Britain to construct larger fleets compared to Japan. Notably, the treaty attempted to resolve differing naval strategies by categorizing cruisers into "heavy" and "light" types, which reflected the varied maritime roles each nation envisioned.
Despite its initial success, the London Naval Treaty was short-lived, as Japan grew increasingly dissatisfied with its status within the agreement. The breakdown of cooperation on naval disarmament ultimately contributed to the escalation of a naval arms race, which played a significant role in the lead-up to World War II. While the treaty represented a notable effort towards controlling military expansion, it also highlighted the complexities of international relations and the challenges of achieving lasting peace through disarmament agreements.
On this Page
London Naval Treaty
The Treaty Pact among the United States, Great Britain, Japan, France, and Italy to regulate submarine fleets and limit warship building
Date Signed on April 22, 1930; took effect October 27, 1930
Continuing the efforts started in the 1922 Washington Naval Treaty, the London Naval Treaty tried to lower international tensions by reducing the size of the major navies of the world. Its terms did limit the size of the major navies, but contentious elements of the treaty later helped to fuel the outbreak of World War II.
In the aftermath of World War I, nations strove to cut their military forces to save money and prevent future conflicts. In 1922, the United States, Great Britain, Japan, France, and Italy agreed to the Washington Naval Treaty, which limited the size and number of battleships and aircraft carriers a nation could possess. The United States and Great Britain received the largest authorization, Japan receiving a smaller authorization, and France and Italy were permitted only small numbers of capital ships. Because the Washington treaty did not address all types of warships, the five nations continued discussions on naval disarmament, talks that culminated in the 1930 London treaty. France and Italy opted not to sign the treaty.
The main participants in the naval talks, the United States, Great Britain, and Japan, generally agreed on limitations on the size and number of destroyers and submarines. The treaty permitted the United States and Great Britain to each construct up to 150,000 tons of destroyers, while Japan could build 105,500 tons. Individual destroyers could not exceed 1,850 tons displacement, nor have a gun armament greater than 5-inch caliber. This prevented the signatories from building larger ships but disguising their capability by labeling them as destroyers. The treaty authorized an equal tonnage in submarines to all nations of 52,700 tons. The agreement limited submarine displacement to 2,000 tons and armament to 5-inch caliber.
The three nations disagreed on definitions and limitations on cruiser construction. Smaller than battleships but bigger than destroyers, cruisers were effective, multipurpose ships with heavy armament and long range. The three navies differed on how they used cruisers and, therefore, disagreed on how many cruisers to authorize and how the ships were to be armed. The United States employed cruisers as scouts and escorts for its main battle fleet, so it wanted a relatively small number of heavily armed ships. The British used cruisers to police their global empire, so they favored a larger number of lightly armed ships. Because the Washington treaty granted them fewer battleships, the Japanese wanted a large number of heavily armed ships to support their battleships in a fleet engagement. The solution was to divide cruisers into two distinct categories that permitted the respective nations to construct limited numbers of the types they wanted.
The London treaty grouped cruisers as “heavy,” ships larger than 1,850 tons but less than 10,000 tons and gun armament greater than 6-inch caliber, or “light,” ships larger than 1,850 tons but less than 10,000 tons and gun armament limited to a maximum of 6-inch caliber categories. The treaty permitted the United States to construct 180,000 tons worth of heavy cruisers to escort the battle fleet and 143,500 tons of light cruisers to serve as scouts. The British navy, however, could construct 146,800 tons of heavy cruisers but 192,200 tons of light cruisers to provide enough ships to patrol their empire. As with the Washington treaty, the Japanese received a smaller authorization than the United States and British of 108,400 tons of heavy cruisers and 100,450 tons of light cruisers to augment their battle fleet.
Impact
The London Naval Treaty was the last successful naval disarmament treaty of the interwar period, but its success was short-lived. Japan, unhappy with its second-class status relative to the United States and Great Britain, refused to extend the terms of the Washington and London treaties, and the subsequent naval arms race helped to trigger World War II.
Bibliography
Goldman, Emily O. Sunken Treaties: Naval Arms Control Between the Wars. University Park: Pennsylvania State University, 1994.
Hammond, James W. The Treaty Navy: The Story of the US Naval Service Between the World Wars. Bloomington, Ind.: Trafford, 2006.
Morley, James William. Japan Erupts: The London Naval Conference and the Manchurian Incident, 1928-1932. New York: Columbia University Press, 1984.