HMS Campbeltown was originally the Wickes-class destroyer USS Buchanan, DD-131. She was commissioned in 1919 and transferred to the UK as part of the “Destroyers for Bases” deal between the US and Britain in 1940. In exchange for 50 aging “four-piper” destroyers like the Buchanan/Campbeltown (obsolete for fleet duties, but still useful as convoy escorts) for the Royal and Royal Canadian navies, the US got basing rights in the Caribbean and Newfoundland.
HMS Campbeltown is one of the most well-known of the traded ships, as she was famously expended as a floating bomb in the “Operation Chariot” raid by British commandos on the St. Nazaire docks in March of 1942. The purpose of the raid – and it succeeded – was to deny the use of the St. Nazaire dry dock to heavy German units such as the battleship Tirpitz.