The destroyer dropped a pattern of depth-charges which exploded below the U-Boat, inflicting considerable damage. There was water entry forward between the bow torpedo tubes. A sea inlet valve of the Diesel cooling system was fractured causing water to flow into the motor room. “U 73” lost trim and sank to a depth that was variously estimated to have been between 160 and 230 m. (524.8 and 754.6 ft.).
Undertaking this patrol prior to the launching of our first large-scale offensive in the Pacific, Captain Cromwell, alone of the entire Task Group, possessed secret intelligence information of our submarine strategy and tactics, scheduled Fleet movements and specific attack plans. Constantly vigilant and precise in carrying out his secret orders, he moved his underseas flotilla inexorably forward despite savage opposition and established a line of submarines to southeastward of the main Japanese stronghold at Truk.