Australia’s navy was too British to switch sides cleanly

Could Australia join the United States in a war against Britain?

Not plausibly in 1914. Australia was even less prepared than the United States, and much of its naval personnel and institutional base remained directly British.

Possession of the battlecruiser HMAS Australia did not make the Commonwealth an autonomous great naval power. A substantial part of the Royal Australian Navy’s personnel and professional structure was still British, including sailors who were not even first-generation Australians. An attempt to fight Britain could split loyalties and leave the government without a reliable fleet. Australia also lacked the broader military and industrial readiness needed to replace that support quickly. Institutional dependence and personnel identity mattered as much as the flag flown by the ships.