The second half of the nineteenth century was one of uncertainty for the British Empire and its collective security. The British Navy League emerged in 1895 out of anxieties about the state of the Royal Navy and imperial defence, and established branches throughout the Empire. The First World War left Great Britain, the United States and Japan as the three major naval powers in the world, all with vested interests in the Pacific. By the end of 1938, Gambia and Zanzibar had also formed their own Naval Volunteer Forces, while Penang hosted a Malayan branch of the Royal Naval Volunteer Reserve (RNVR). British naval and imperial power relied on psychological as well as physical fortification. The chapter shows that naval theatre continued to be deployed in support of colonial naval forces and imperial prestige until decolonisation.