X-Nico

4 unusual facts about Washington Naval Treaty


Great War at Sea series

Studying the actual plans of the United States Navy and Imperial Japanese Navy, Plan Orange attempts to recreate what a war in the Pacific would have been like in 1930 if there had been no Washington Naval Treaty.

Plan Z

The Washington Naval Treaty classified battlecruisers in the same category of capital ship as fast battleships because that reflected post-World War I naval thinking.

Washington Naval Treaty

It also contributed to controversy in high ranks of the Imperial Japanese Navy between the Treaty Faction officers and those opposed to it, who were also allied with the ultranationalists of the Japanese army and other parts of the Japanese government.

In response, the Japanese parliament finally authorised construction of warships to enable the Japanese Navy to reach its target of an "eight-eight" fleet programme, with eight modern battleships and eight battlecruisers.


20.3 cm/45 Type 41 naval gun

Many of these ships were disarmed under the conditions of the Washington Naval Treaty or subsequent London Naval Treaty and their guns converted into coastal artillery batteries, including installations at Tokyo Bay, Tarawa and later at Wake Island during World War II.

Mineo Ōsumi

Ōsumi, despite his reputation as a liberal, supported the decision to withdraw from the League of Nations and also argued forcefully for higher naval appropriations budget and re-negotiation of the Washington Naval Treaty.


see also