At 08.15 hours on 26 July 1942 U-66 fired a spread of two G7e torpedoes from the stern tubes at the unescorted and neutral Tamandaré (Master José Martins de Oliveira) in hazy weather during a full moon night about 14 miles north of Tobago and hit with both after a running time of 71 seconds. The U-boat had spotted the ship at 06.58 hours, which was armed with a 120mm gun aft and proceeded on a zigzag course at 12 knots without visible nationality markings. The first torpedo struck on port side amidships in the engine room and the other further aft causing a high column of smoke. The explosions killed four crew members on watch below, destroyed both port lifeboats and tore a large hole in the side, causing the ship to quickly settle aft with a heavy list to port until Tamandaré eventually capsized and sank by the stern about 50 minutes after being hit. No distress signals could be sent because the aerial was broken and the generators were out of order. The master, 43 crew members and four gunners had abandoned ship in both starboard lifeboats within 10 minutes and then observed how the U-boat used a searchlight and remained close to the ship for over 30 minutes, but did not move to the starboard side where the lifeboats were. Allied authorities later feared that the Germans had boarded the vessel and captured the routing instructions left behind in a cabin drawer, but in fact they had just tried to identify the ship and waited nearby for her to sink. Four hours after the attack the survivors used a flare to attracted the attention of a patrol aircraft, which was later relieved by two seaplanes until they were picked up by USS PC-492 at 18.10 hours and landed at Port of Spain the next morning.