Japan's decisive-battle lesson and its dangers

Japan learned that a strong regional fleet could exploit distance, attrition, and prepared home waters to defeat an expeditionary opponent in a decisive battle. In this interpretation, Tsushima was a Cannae-like result, while the formal decisive-battle doctrine crystallized after the war even though its theory already informed the Six-Six Fleet. The lesson fed later fleet planning, including the Eight-Eight concept and the search for a favorable capital-ship ratio under the Washington treaty system. Yet the doctrine was fundamentally defensive and could not guarantee success through repeated rounds against a power with much greater industrial depth. Tsushima's prestige, later wartime successes, and a growing siege mentality fed the overconfidence that complicated Japanese strategy before the Pacific War.