At 21.35 hours on 12 Nov 1942 the unescorted Buchanan (Master Arthur Jensen) was proceeding on a nonevasive course at 15 knots, when she was struck by a torpedo from U-224 on the port side at #5 hold. The entire port side in the area of #4 and #5 holds was blown out and the hatches were ablaze. The propeller shaft was broken and the engine stopped. After the vessel was abandoned, a second torpedo hit in the forepeak. The Buchanan remained on an even keel and finally sank after 90 minutes.

All 46 crew members, 15 armed guards and 12 passengers of the US Air Force survived but several were later hospitalized for exposure. The ship was abandoned in four lifeboats, which remained at the spot of the attack until the morning of the next day. The master ordered the boats to set sail and head for Ireland, but a strong wind separated the boats. On 16 November, ten crewmen, five armed guards and three passengers in one boat were picked up by the American motor merchant Lighting and were landed at Liverpool five days later. On 20 November, ten crewmen, five armed guards and two passengers in another boat were picked up by HMS Leamington (G 19) (Lt C.G.L. Bush, RN) and landed at Londonderry. On 21 November, the remaining men were picked up from two boats by HMS Clare (I 14) (LtCdr L.H. Landman, RN) and were taken to Londonderry the next day.