Yamamoto defined Japan's minimum security as six large battleships supported by at least four armored cruisers. He rejected a battle-line-only fleet and compared naval organization to an army whose infantry relied on artillery, cavalry, engineers, and other supporting arms. The resulting program added 23 destroyers and 63 torpedo boats rather than treating small combatants as optional extras. It also expanded Japanese shipyards, repair facilities, and training capacity. The Six-Six Fleet was therefore an infrastructure-heavy force-building project in which support systems were part of combat power.
Chapter · 6:20-7:43
A balanced fleet needs supporting craft and infrastructure
The Six-Six Fleet paired capital ships with cruisers, destroyers, torpedo boats, shipyards, repair capacity, and training facilities.