to a stop with a single destroyer in attendance. Two more torpedoes from Upholder sank her. Wanklyn had accounted for nearly 40,000 tons in the same attack. The gyro-compass had been put out of action during the action. Upholder experienced a barren run over the next few weeks. Her next patrol, between 23 September and 2 October, was north of Marittimo and stretching to Cape St Vito. Two weeks later, in mid-October 1941, the boat operated with Urge in the Kerkenah Bank off Tunisia. On the night of 8 November 1941, lookouts spotted a U-boat in the moonlight off Melito di Porto Salvo. Wanklyn determined it was Italian, possibly a Perla, Sirena or Argonauta-class submarine. A full salvo sank the vessel. No survivors were recovered, and only a large oil slick was visible on the surface. Upholder picked up the noise of the enemy vessel breaking apart as it sank. Just 36 hours later, Wanklyn witnessed the Battle of the Duisburg Convoy. Captain William Gladstone Agnew led Force K—a flotilla of several destroyers—into a surface battle. Speeding up to attack any stragglers, Wanklyn engaged and sank the Italian Maestrale-class destroyer Libeccio. Wanklyn attempted to engage a cruiser but hit an Avieri–class destroyer, which he claimed damaged. During the battle the gyro failed on one of the Upholder torpedoes, which ran in circles and came close to the Upholder before sinking. Last patrols On 25 November 1941 Upholder left for her eighteenth patrol. Wanklyn positioned the submarine south east of the Messina straits. At 07:30 on the 27 November they sighted a large tanker with destroyers for escort. Wanklyn fired a full salvo at 2,800 yards but underestimated the enemy's speed. This convoy was later intercepted, and the tanker sunk, by Force K. On 29 November Upholder sailed into the midst of an Italian naval squadron on a night exercise. The enemy fleet consisted of three cruisers and five destroyers. With the closest vessel only 3,000 yards away Wanklyn continued to calculate the bearing and speed of the enemy, until eventually he ordered the boat to dive. He could not see anything through the periscope in the winter night. By using dead-reckoning, he fired off a salvo at the last ship using his asdic. The target disappeared on a reciprocal bearing and then reappeared right over the top of Upholder. Wanklyn docked at Malta on the morning of 21 December 1941.