I don't think I've posted this yet here. It's from my October 2009 AH Newsletter.
What Actually Happened: After World War I, the US was in a position to quickly displace the British Royal Navy as the strongest naval power in the world. The US had enough powerful modern battleships and battlecruisers in the

ipeline that by 1924 the US navy would surpass the British. Given the lead time for building new capital ships, the British could not avoid being surpassed, even with a massive national effort. The British would still have more capital ships, but most of them would be older and far less powerful than the ones in the US fleet.
In spite of that seemingly powerful position, the US had a problem. In the aftermath of World War I, isolationism was growing and it was looking increasingly likely that many of those new ships would be scrapped rather than being completed. The US basically bluffed on a weak hand. Great Britain and Japan knew that the US could outbuild them if it chose to do so. The US offered to give up its potentially dominating position in favor of parity with Britain and near-parity with Japan—a 5-5-3 ratio in capital ships. That meant that the US would scrap most of the powerful new battleships and battle cruisers it was building. In return, the British would scrap enough older ships to get to tonnage equality with the US. The Japanese would scrap several ships they were building and agree to overall inferiority to the US and Britain in capital ships. The US proposed a ‘battleship holiday”—essentially no more building of battleships for 10 years. That didn’t quite happen, but it came close. In addition the treaty limited the tonnage of battleships and aircraft carriers the powers could build. It limited the size and armament of the cruisers the powers could build, so that cruisers didn’t become battleships in everything but name. A treaty cruiser had 8 inch guns and theoretically weighed 10,000 tons. Many of the naval powers cheated a little on the limits. The Japanese cheated quite a bit, and ended up with more effective cruisers because of the cheating.
The Washington naval treaty shaped the US, British and Japanese fleets of the early part of World War II. It finally broke up when the Japanese refused to renew it in the mid-1930s, but most of the ships of the early part of World War II were either allowed to remain in service due to the Washington naval treaty or were built within treaty limitations.
The treaty also forbade the US and Britain from building new fortifications and certain other types of facilities in the Far East. That left the Philippines less fortified than the US wanted them to be, and left Guam essentially defenseless.