The 1920s and 1930s planning papers sit alongside a peaceful transfer of naval predominance between states that fought together in both world wars. Staff planners still needed the strongest conceivable opponent against which to test force employment, making the United States and Britain natural benchmarks for each other. Hypothetical Anglo-American conflict was therefore useful for professional exercises without proving that either democracy expected war. Plans against Japan also existed but were more sensitive, so Anglo-American planning papers must be read in their professional and diplomatic context rather than as straightforward evidence of intent.
Notable Point · 23:47-25:45
Why US-Royal Navy planning papers should not be read as imminent war plans
Interwar US and British planning used the other navy as the toughest conceivable opponent even as naval predominance passed peacefully between two wartime allies.