At 16.05 hours on 21 Dec 1940 the unescorted, unarmed and neutral Charles Pratt (Master Eric R. Blomquist) was hit amidships by one torpedo from U-65 about 220 miles off Freetown. Stockhausen had clearly seen the Panama flags painted on her sides, but decided to attack without warning as the tanker was obviously heading for an enemy port. The torpedo hit on the starboard side at #6 tank blowing out the bulkheads in #6 main tank and #4 summer tank and also the deck plates in the way of the pump room. The blast showered oil and debris clear to the top of the mast and over the boat and poop deck. The tanker caught fire at once and burning oil flowed into the starboard alleyway. Steam smothering lines were opened but to no avail as all lines were destroyed in the pump room. The survivors abandoned ship immediately in both port lifeboats. After 20 minutes, the tanker was struck on the starboard side by a second torpedo just forward of the midship house, blowing burning oil and debris several hundred feet in the air and showering the water with oil and steel fragments, some just missing a lifeboat. The second explosion put out the fire but the flooding eventually caused the ship to sink with a heavy list.

The lifeboats remained in the vicinity to search for three missing men and after 40 minutes rescued the chief mate who suffered various injuries including a broken leg. He and second crewman had been blown overboard by the explosion, but the other man was not found. At nightfall, they tried to return to the ship to get medical supplies and to repair the radio because no emergency message had been sent due to damage to the aerial, but could not locate the tanker anymore. The boats then set sail towards Freetown and were separated on the evening of 24 December. At 15.00 hours on 25 December, the survivors in the lifeboat of the master were picked up by the British motor merchant Gascony about 60 miles west of Freetown and were landed there the following morning. On the afternoon of 26 December, the survivors in the other boat were picked up by the British steam merchant Langleegorse and were also landed at Freetown the next morning.