Simpson ordered her to participate in operations of the Libyan coast. On the morning of 23 February, Upholder took up her position off Misurata. Wanklyn pursued two ships until he realised they were destroyers. On 26 February Upholder picked up a contact of Sidi Blal. He closed to attack on the surface before appreciating his error—his quarry was another destroyer. Wanklyn ordered the boat to dive. Apparently they had sailed so close Wanklyn saw the sparkle of a cigarette thrown from the destroyer. Off Tripoli Upholder intercepted the transport Tembien and her single destroyer escort. Wanklyn ordered three torpedoes fired and three hit. The cargo ship sank in twenty minutes. From 28 February—3 March, no more vessels were encountered and Wanklyn docked in Malta on 5 March. Tembien was carrying 468 Allied prisoners of war, a fact known to the British through Ultra decryptions. Her sinking caused the deaths of at least 390 prisoners and 78 crew and guards. On 14 March 1942, Wanlyn departed on his 27th patrol in the Gulf of Taranto. On the night of the 18 March he sighted a submarine on the surface and determined her to be hostile. He engaged with a full spread of torpedoes, and the submarine blew apart and sank. The submarine, later identified as the Tricheco, was lost with all hands. There was no counterattack, but motor torpedo boats shadowed her movements for hours which ran down her battery and oxygen. The following day Wanklyn moved to St Cataldo Point hoping to find a softer target for his deck gun. The lookouts sighted four vessels, a trawler and three fishing smacks. Wanklyn ordered the submarine to surface 100 yards from the trawler, Maria. His officers gestured to the crew to abandon ship and Upholder fired seven shells into the vessel which sank. The smacks fled close to shore. The action had lasted 14 minutes and Wanklyn decided it was too dangerous to give chase. On 23 March Upholder, Proteus and P36 loitered off Taranto in the hope of engaging Italian warships. One convoy was sighted and Wanklyn fired on a light cruiser but missed. All three returned to Malta without success. Death Wanklyn is believed to have been killed along with his crew when Upholder was lost on her 25th patrol, becoming overdue on 14 April 1942. The most likely explanation is that she fell victim to depth charges dropped