Arthur Johns's 1934 paper describes carriers as a necessary warship type already bounded by treaty rules. Britain and the United States received 135,000 tons each, Japan 81,000, and France and Italy 60,000 each, encouraging navies to trade individual ship size against fleet numbers. The Royal Navy's interest in roughly 22,000-ton designs reflected the possibility of fitting about six carriers within its national allowance instead of five ships at the normal maximum. A special allowance for two ships up to 33,000 tons enabled Lexington, Saratoga, Akagi, and Kaga to emerge from unfinished capital-ship hulls; earthquake damage to Amagi caused Kaga to replace her.
Chapter · 6:55-11:43
How treaty quotas shaped early carrier fleets
The Washington and London treaties set national carrier tonnage, unit size, and gun limits while allowing two large battlecruiser or battleship conversions.