its convoy traffic. On 25 April Wanklyn spotted a merchant ship and its armed trawler escort but managed to close to 700 yards undetected before firing two torpedoes. The ship was hit and sank. It was later identified as the small merchant vessel Antonietta Lauro, which was loaded with nitrates bound for Italy. She sank slowly, and went under after six hours. The following day, 26 April, he spotted two ships that had run aground. He waited for darkness so that he could escape under cover, and closed on the merchant and its destroyer escort, hoping to torpedo both. As he closed to eliminate the destroyer first he ran aground in 29 feet of water. Unable to risk torpedoes in such shallow water, he moved alongside the transport, which had been heavily damaged in an attack and appeared to be deserted, with no live personnel on board. The deck was covered in motorcycles, cars and trucks earmarked for the Afrika Korps. Wanklyn ordered a boarding party to loot whatever they could and lay scuttling charges, which blew up the ship. He elected to leave the destroyer, which lay in much shallower water, until the following day. Wanklyn ran aground again and was forced to abandon the attack, returning to base with Arta as his solitary kill. In North Africa, German forces had gone onto the offensive in Operation Sonnenblume. By late April British Army forces were being forced out of Libya and Tobruk was surrounded. Simpson ordered his submarines to intercept convoys sailing from Naples and delivering supplies to the Axis armies in Africa. To assist, Horton formed the 5th Destroyer Flotilla with the light cruiser Gloucester as support. Simpson sent Upholder, Ursula and Upright. Simpson ordered his submarines into action on 27 April and 1 May. On 1 May 1941, Upholder and Ursula gained contact with a convoy, but the ships were travelling too fast to close to effective range. Six hours later he spotted five transports with four destroyers conducting zig-zagging courses to avoid underwater attacks. The water was rough but Wanklyn fired a three-torpedo salvo at the two largest, overlapping, vessels. Three explosions were heard. The German liner Leverkusen, which had been hit twice, sank by the stern. The third torpedo had stopped Arcturus, which was listing heavily by the bow. The enemy delivered a moderate counter-attack and sped off. Wanklyn used his final two torpedoes to