On November 19, 1943, during the ninth war patrol of the U.S.S. Sculpin in enemy-controlled waters off Truk Island, Captain Cromwell commanded a coordinated submarine attack group and, alone in the task group, held secret intelligence on submarine strategy and tactics, scheduled fleet movements, and specific attack plans before the first large-scale offensive in the Pacific. Vigilant in carrying out his orders, he moved the flotilla forward despite heavy opposition and established a line of submarines southeast of Truk. After Japanese depth charges badly damaged Sculpin and drove her to an excessive depth, he authorized the submarine to surface and fight the enemy with guns, giving the crew a chance to abandon ship. Choosing death over capture and the risk that torture or drugs might force disclosure of secret plans, he remained aboard the mortally wounded submarine as it sank, preserving mission security at the cost of his life.