Washington Treaty 1922

The Treaty

Background By the end of World War 1, large numbers of warships had been made obsolete, or were prematurely heading for obsolescence by the advance of Technology during the war. (Mainly submarine warfare and the coming emergence of aircraft).

Until the early part of the 20th century, Britain had a policy of maintaining the Royal Navy's strength to be at least equal to the next two naval powers combined.

The emergence of the USA from isolationist policies together with it's huge industrial strength, plus the militarisation of Japan meant Britain would need a huge building program to maintain the ratio of RN capital ships to other navies.

Britain's, France's and Italy's bankruptcy due the cost of World War 1 meant a new world naval military order was needed. Otherwise international tensions would rise as the USA and Japan would not countenance the old Royal Navy domination of the world's trade routes.

In addition another Naval Arms Race could not be contemplated due to the costs and war weariness in Britain, it's Empire, France and Italy.


Washington Treaty 1922

Ships Retained By

Ship Replacement Table


The objective To control costs, and reduce international tensions in the post World War 1, world.

Especially after considering the tensions caused by the naval build up by Germany from about 1906 to the start of WW1, and Britain's response to this.


What was agreed The world's main naval powers - Britain; it's Empire and Dominions; the USA; France; Italy; and Japan agreed.
To limit,
- the overall total tonnage,
- the individual size,
- the overall tonnage,
- the calibre of guns,
for all ships covered by the treaty. (Ships greater than 10,000 tons standard displacement and emerging aircraft carrier fleets.)

In addition it
- set down when any ship covered by the treaty would be scrapped and replaced.
- set gun calibre limits for ships displacing 10,000 tons or less.
- banned preparation in time of peace, of Merchant ships for later conversion to warships.
- banned warships being constructed for non-treaty powers being taken over by treaty powers in time of war.
- froze construction of new naval bases and fortifications in the Pacific, by the British Empire, USA and Japan.
- banned transfer of warships to non-treaty powers.


Ending the Treaty The Treaty was to continue in force until at least 31-Dec-1936, unless any signatory gave notice by 31-Dec-1934 of its intention to terminate the Treaty.

If no notice to terminate had been given by 31-Dec-1934, the Treaty would continue until 2 years after any signatory gave notice of its intention to terminate.


Capital Ship Limits The overall total standard displacement tonnage for each power set at;

United States  - 525,000 tons (533,400 metric tons);
British Empire - 525,000 tons (522,400 metric tons),
France             - 175,000 tons (177,800 metric tons),
Italy                   - 175,000 tons (177,800 metric tons),
Japan               - 315,000 tons (320,000 metric tons).

The maximum standard displacement for any ship to be 35,000 tons (35,560 metric tons).

The maximum calibre of gun was 16 inches (406mm).


Aircraft Carriers The overall total standard displacement tonnage for aircraft carriers set at;

United States  - 135,000 tons (137,160 metric tons);
British Empire - 135,000 tons (137,160 metric tons);
France             -    60,000 tons (60,960 metric tons);
Italy                   -    60,000 tons (60,960 metric tons);
Japan               -    81,000 tons (82,296 metric tons).

All existing aircraft carriers were considered experimental and could be replaced at any time provided the total tonnage limit was not exceeded. Two Aircraft Carriers for each power could not exceed 33,000 tons standard displacement, with all others limited to no more than 27,000 tons.


Replacing Capital Ships A schedule of scrapping and replacing ships for each country was listed until 1942.

This also ensured existing British tonnage which exceeded it's treaty limit, would progressively reduce and comply with the new limit.


Ships up to 10,000 tons The solution to placing similar limits on cruisers and smaller warships was left until the London Treaty of 1930.




This page last edited - 04 February, 2013.

Copyright Ian M King, except where otherwise indicated.