OPERATION " SWAMP " AND THE DESTRUCTION OF " U 593 " IN THE MEDITERRANEAN 13th December 1943 This operation was used in December, 1943, to destroy " U 593 " which had attacked a convoy off the Algerian coast. It aims at covering with aircraft the area in which it is anticipated that a U-Boat can move after its presence has been disclosed and is naturally most effective where the enemy is forced to operate against ships proceeding coastwise and within about 30 miles of land. As soon as a U-Boat has disclosed its presence, strike aircraft are despatched to cover a semicircular area around the position and surface forces are detailed to act as an A/S striking force to prevent the U-Boat from escaping, it is necessary that each part of the area should be swept either visually or by radar at half-hour intervals. As the search continues, the air cover must be spread by increasing the radius of the semi-circle, it being assumed that the U-Boat may travel at two knots during the first 24 hours and, thereafter at one knot, as long as it is kept submerged. The operation is planned in eight-hour phases, the area being increased at the end of every eight hours and, as at present designed, calls for 86 flying hours on patrol during the first 24 hours and 144 flying hours on patrol during subsequent periods of 24 hours, when six aircraft will be on patrol at any one time. The sinking of H.M.S. " Tynedale " at 0710 on 12th December was the executive for putting the operation in force. Three Wellington aircraft of 458 Squadron at once started from Bone to cover the semi-circular area round the position of the sinking and later in the day Leigh Light Wellingtons of 36 Squadron were sent from Blida to Bone in preparation for night operations. H.M.S. " Holcombe " and U.S.S. " Niblack " began to hunt immediately after " Tynedale " had been sunk and H.M.S. " Calpe " and U.S. Ships " Wainwright " and " Benson " were also ordered to join. At 1505 " Holcombe " was torpedoed and sunk about 15 miles from where " Tynedale "had gone down. The attack was witnessed and reported by an aircraft of 36 Squadron on its way to Bone and Operation Swamp was begun afresh, the position of the second attack being now taken as the centre of the area to be covered. Shortly after midnight the night of the 12th/13th, Wellington aircraft 13/36 detected the U-Boat by radar but its attack was beaten off and, extensively damaged, it could only machine-gun the U-Boat and report the incident. It had, however, considerably assisted the operation to the U-Boat, which had surfaced to charge her batteries, dived at once, and only surfaced again for a short period later in the night. Operation Swamp was now adjusted for the third time, the position of this sighting being taken as the new centre, but it was not until about 1430)13 that " Wainwright " and " Calpe " found the U-Boat and attacked with one 5-charge pattern and two 10-charge patterns respectively. As a result of these attacks water poured in and, with her high pressure air exhausted, the U-Boat surfaced with difficulty and was scuttled. Since the attack on " Tyucclale " 32 hours earlier, she had only been able to spend a matter of minutes on the surface. In the same period of 32 hours 21 Wellington sorties had been flown.