Crew of U-550 prepares to abandon ship on April 16, 1944. Photo
taken from USS Joyce (DE-317). The twenty-one ships of Convoy
CU-21 included SS Pan Pennsylvania, at the time the largest
tanker in the world. CU convoys brought fuel to the United
Kingdom after the North African landings had taken temporary
priority. She carried 140,000 barrels of aviation fuel, fifty
crew, and thirty-one armed guard. Board for the United Kingdom,
CU-21 left New York on April 15, 1944. Her escort included five
Destroyer Escorts of Task Group 21.5 of Escort Division 22
operated by United States Coast Guard crewmen, and one United
States Navy Destroyer Escort. As the convoy formed up in the
Atlantic Ocean off New York City, SS Pan Pennsylvania took her
station in the convoy. U-550, commanded by Kapitanleutnant Klaus
Hanert (February 1, 1918 - ????), had been lying in wait off New
York for just such a target. She was one of only three U-boats
to brave the long-range aircraft and hunter-killer task groups
to attack Allied shipping.