At 03.50 hours on 28 June 1942, U-154 fired a single torpedo at an unescorted zigzagging steamer with East course and scored a hit amidships after 18 seconds. The ship sank after 2 minutes 30 seconds and only left a few survivors on a raft and clinging to debris. The survivors were questioned by the Germans, but they were hard to understand due to the heavy seas and because they all yelled together in great confusion. The vessel was identified as Clyde with 3200 grt, but no such vessel could be found in the ship listings.

The Tillie Lykes (Master Gus Warren Darnell) was reported missing with the eight officers, 21 crewmen and four armed guards (the ship was armed with one 3in and two .30cal guns) on board after leaving Galveston and was incorrectly considered lost by war cause in the Yucatan Basin in approximately 19°N/85°W on 18 June when she was actually lost on 28 June about 100 miles south of Santo Domingo, Dominican Republic.

The master Gus Warren Darnell had been in command of Cardonia when she was sunk by U-126 (Bauer) on 7 March 1942.