 In August 1943, Portugal signed the Luso-British agreement, which leased bases in the Azores to the British.This was a key turning point in the Battle of the Atlantic, allowing the Allies to provide aerial coverage in the Mid-Atlantic gap; helping them to hunt U-boats and protect convoys.Churchill surprised members of parliament (MPs) when he said he would use a 14th-century treaty; many MPs had not known that Portugal and England had the oldest operational alliance in the world, the Anglo-Portuguese Treaty of 1373.