On 29 Dec 1944 the Black Hawk (Master William Leroy Bunch) was travelling in the two column convoy TBC-21 as the last ship in the starboard column, when convoy was attacked by U-322 seven miles southeast of Portland Bill Lighthouse. The two Liberty ships Arthur Sewall and Black Hawk were torpedoed and damaged beyond repair, while the U-boat was sunk by the escort shortly after the attack.

The Black Hawk was struck by one torpedo two minutes after the Arthur Sewall was hit 500 yards off the bow. The torpedo struck on the port side at the #5 hatch, set off the after magazine, completely destroyed the after section of the ship and shot flames and smoke 150 feet into the air. The engines were immediately secured as the ship sank by the stern. A crack appeared at the #3 hatch and water entered #3 and #4 holds and the engine room until only the forward two compartments kept the ship afloat. 30 minutes after the attack, the seven officers, 34 men and 27 armed guards (the ship was armed with one 5in, one 3in and eight 20mm guns) and one Army security officer began to abandon ship in four boats and two rafts. The men were picked up by HMS Dahlia (K 59) (Lt G.V. Ward, RNR) and landed at Brixham at 20.30 hours. Four men were injured and the cook died ashore in a hospital.

A salvage crew later boarded the vessel to prepare her to be towed to Worbarrow Bay, where she was beached an declared a total loss.