Muncastle Castle was a Motor Merchant vessel completed 1928 by Cammell Laird & Co Ltd, Birkenhead. Her homeport was Liverpool. She was travelling the route Glasgow - Freetown (28 Mar) - Capetown – Colombo. Ships complement of 353 (24 dead and 329 survivors). Cargo capacity 265 passengers and 3000 tons of government stores and trucks.

At 22.43 hours on 30 Mar, 1942, the Muncaster Castle (Master Harold William Harper) was hit by a two torpedo spread from U-68 south-southwest of Monrovia (in position 02.02N, 12.02W). The U-boat earlier observed that the ship was in a small convoy of eight ships and one corvette which was dispersed at 13.35 hours and followed the heavy zigzagging ship, running at 13 knots, until she stopped zigzagging in the darkness. The vessel settled immediately after the hits but did not sink and Merten had to use his last torpedo as a coup de grâce at 23.16 hours. After the ship sank by the bow, the U-boat observed more than ten lifeboats and went to one to questioning the survivors, before leaving the area on home course.

Four crew members, one gunner and 19 passengers were lost. The master, 69 crewmembers, eleven gunners, two naval signalmen and 246 passengers were picked up by the HMS Aubretia (K 96) (LtCdr V.F. Smith DSO) and the Greek steam merchant Ann Stathatos and landed at Freetown.

The master, Harold William Harper, was awarded the Lloyds War Medal for bravery at sea and a posthumous OBE.