 During the Second World War, the harbour supported Royal Navy and Royal Canadian Navy ships that were engaged in anti-submarine warfare.It was the site of an American Army Air Force base, Fort Pepperrell, that was established as part of the "Lend-Lease" Destroyers for Bases Agreement between the United Kingdom and United States.The base included several US-manned coast defence guns, and a Canadian-manned battery of two Lend-Lease 10-inch M1888 guns was at Fort Cape Spear.