Build an Australian submarine force before the Pacific war

With British attention fixed on Europe, Australia needed forces suited to local defense and an industrial program it could sustain. Second World War submarines spent much of their time on the surface, unlike modern boats designed to remain submerged, and later levels of air and satellite surveillance did not yet exist. Those conditions made a domestically supported conventional submarine more attainable than a modern comparison might suggest. Australia still needed a yard capable of building and supporting the boats, so the program was both a force-structure choice and an industrial investment.