Though Great Britain possessed the world's greatest Naval fleet, the tradition-bound Lords of the Admiralty overlooked the fact that spread as its responsibilities were across the globe, it now had to defend its far-flung dominions against enemies technologically advanced over any ever fought before. By 1938 it was readily apparent that the flimsy aircraft and vulnerable submarines of the Great War of 1914-18 had developed into formidable long-range weapons now able to decimate entire cities and fleets. The era when proud warships and sword-wielding cavalry could dominate world politics had come to an end. Not without reluctance, the British Admiralty admitted the war of the future would be fought in the sky and beneath, as well as on the sea
So it was late in 1938 that Royal Navy planners came to the conclusion the British Fleet seriously lacked ships able to wage coastal or ocean warfare against Hitler's growing armada of more than 600 swift, deadly, long-ranged U-boats. Despite the Royal Navy's awesome number of destroyers with suitable anti-submarine weaponry, these fleet-footed greyhounds were needed to protect the equally awesome number of capital surface warships. The dismal truth was that no single, capable, coastal or ocean-going anti-submarine escort vessel existed in suitable numbers within the Royal Navy.
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