Naval restrictions placed by the Five-Power Naval Limitation Treaty 1922

The Washington Naval Conference of 1921-22 was an international conference that sought to limit naval armament between the Great Powers and bring lasting peace to the Pacific. The conference was led by the United States, and largely involved France, Italy, Japan, the United Kingdom, and the U.S.. The Five-Power Naval Limitation Treaty placed restrictions on the size of each power's respective military fleet, and a total of almost two million tons of warships were scrapped as a result. Not only did the treaty affect existing warships, but many ships under construction had to be abandoned. There were also restrictions on the maximum weight of ship displacement (35,000 tons) and caliber of weapons on board (16 inches).

The stipulations of the treaty did not grant the powers five equally-sized navies - the UK and U.S. maintained the largest navies, followed by Japan, and then France and Italy (at tonnage ratios of roughly 5 : 3 : 1.67). These measures were not initially welcomed by the Japanese delegation, but territorial concessions were made elsewhere for their appeasement. The treaty was signed in February 1922, and was in effect until the end of 1936. When new terms were being discussed in London in March 1936, Japan requested equal status to the U.S. and UK but this was denied - Japan then formally withdrew and the treaty expired in December 1936. Thereafter Japan's naval rearmament began, in what proved to be a significant development in the build-up to the Second World War.