also sank Serroskerk in mid-Atlantic. There were no survivors. Fifth patrol U-155s fifth sortie involved her move to the western Caribbean and southern Florida, USA. She sank Lysefjord west of Havana on 2 April 1943, and on 3 April sank the oil tanker Gulfstate about east northeast of Marathon Key, Florida (in 2013 the National Oceanic and Atmospheric Administration's Remediation of Underwater Legacy Environmental Threats (RULET) project found the sunken Gulfstate to be a potential source of oil pollution.) On the return journey U-155 was attacked by an unknown aircraft on 27 April northwest of Cape Finisterre, Spain. Sixth patrol To try and counter the air threat, U-155 was grouped together with , , and in the Bay of Biscay. The formation was attacked by four de Havilland Mosquito aircraft on 14 June — three from No. 307 Polish Night Fighter Squadron and one from No. 410 Squadron RCAF. One Mosquito, hit in the port engine, was forced to break off its attack and return to base where it made a belly landing. Five men in the boat's crew were wounded; they were treated by U-68s doctor on their return to Lorient on 16 June. Seventh and eighth patrols Patrol number seven was as long as any of the others, to a point northeast of the Cape Verde Islands; but the boat did not find any targets. The submarine's eighth patrol took her toward the northeast coast of Brazil. While sinking Siranger she took the third mate prisoner (he had been wounded, and was operated-on by the boat's doctor). He was taken back to Lorient and was eventually transferred to the POW camp at Milag Nord near Bremen. Ninth and tenth patrols U-155s ninth patrol was, at 105 days, her longest, but like her seventh, found no targets. On 4 May 1944, the boat shot down a North American P-51 Mustang aircraft of No. 126 Squadron RAF and on 23 June 1944, Mosquitos of 248 Squadron attacked, killing Matrosenobergefreiter Karl Lohmeier and Mechanikerobergefreiter Friedrich Feller and wounding seven others. Her patrol terminated at Lorient the same day. Her tenth and final patrol left Lorient on 9 September 1944, the last by a U-boat from the base. The patrol was uneventful; she returned to Germany by a circuitous route, and docked at Flensburg on 21 October. Fate On 22 June 1945, after the German surrender, she was transferred from Wilhelmshaven to