By October 1939, Dönitz had decided to use three longer-range boats to intercept the first Allied convoys of the war. , and were to rendezvous southwest of Ireland before attempting to force the Straits and attack the convoys in the Mediterranean. Things went quickly wrong, "U-25" was diverted to a convoy south-west of Lisbon. After an abortive torpedo attack on a steamer on 31 October, Viktor Schütze, "U-25"s commander, surfaced and proceeded to sink his target with fire from his deck gun. This course of action caused a crack in a vital part of the submarine, obliging the boat to return to Germany. "U-53" ran low on fuel after shadowing a convoy in the Bay of Biscay and was also forced to return. "U-26", was compelled by a combination of unsuitable weather, searchlights and British anti-submarine patrols, to abandon an attempt to lay mines near Gibraltar harbour. The boat sailed through the Straits on the surface and claimed but a solitary ship sunk in the Mediterranean. This 'sinking' was not confirmed by post-war analysis.