Two weeks after the war began for Britain, "HMS Courageous" was on an anti-submarine patrol with only a small screening force. It was sunk by "U-29". HMS "Ark Royal" might well have been sunk the same week by "U-39" if the U-boat's torpedoes had not been defective. Thereafter, such carriers were regarded by the Admiralty as too vulnerable to be used for anti-submarine patrols. Eight months later, "HMS Glorious" was evacuating aircraft during the British withdrawal from Norway. She left the main body of its fleet and was discovered by two German battleships. Alone, without aircraft aloft and with only 4-inch guns to protect herself, she was sunk by the battleships' 11-inch shellfire. "Glorious" was the first aircraft carrier ever to be sunk by warship gunfire. Her commander had not launched bombers to protect her from such warships, perhaps in part because her decks were crowded with fighters recovered from Norway airfields that she was transporting back to Britain. Even if aircraft had been deployed, however, the outcome may have been the same. British torpedoes, like those used by Germany and America at the time, were defective and often detonated prematurely or did not detonate at all. Similarly, British anti-submarine bombs aboard "Glorious" at the time had almost no destructive power