The British were determined to neutralise "Tirpitz" and remove the threat she posed to the Allied arctic convoys. Following the repeated, ineffectual bombing attacks and the failed Chariot attack in October 1942, the British turned to the newly designed X Craft midget submarines. The planned attack, Operation Source, included attacks on "Tirpitz", "Scharnhorst", and "Lützow". The X Craft were towed by large submarines to their destinations, where they could slip under anti-torpedo nets and each drop two powerful two-tonne mines onto the sea bed under the target. Ten vessels were assigned to the operation, scheduled for 20–25 September 1943. Only eight of them reached Kåfjord in Norway for the attack, which began early on 22 September. Three of the vessels, "X5", "X6", and "X7", successfully breached "Tirpitz"s defences, two of which—"X6" and "X7"—managed to lay their mines. "X5" was detected from the nets and sunk by a combination of gunfire and depth charges.