Between 21.45 and 22.00 hours on 5 July 1944, U-763 fired two Gnats and one LUT torpedo at ships in convoy FTC-27 in the English Channel about 20 miles southeast of Selsey Bill and claimed to have hit two steamers and probably damaged a destroyer after hearing three detonations. In fact, only the Glendinning (Master Donald MacAskill) was hit on the starboard side between #2 hatch and the bridge by one torpedo that completely blew off the forward part. She was the ship of the vice-commodore in station #11, leading the starboard column of convoy which proceeded in two columns in fine weather at 7.5 knots. The majority of the 24 crew members, seven gunners (the ship was armed with five 20mm and four machine guns) and two passengers (a naval signalman and an army storekeeper) abandoned ship in the port lifeboat after about 15 minutes, while others jumped overboard and clung to wreckage when the ship gradually listed to starboard until capsizing and sinking with the stern high in the air at 22.26 hours. One crew member, one gunner and the army storekeeper were lost.

The port lifeboat with 23 occupants searched the wreckage and rescued the three engineer officers and the gunlayer, while the chief officer and radio operator were picked up by HMS ML-250 (LtCdr J.D.S. Header, RN) of the 19th ML-Flotilla and two of its officers dived overboard to rescue the master who was unconscious and suffering from a fractured skull. The motor launch then took the survivors off the lifeboat and eventually transferred them all to HMS Fernie (L 11) (Lt J.A. Tricker, RN) at 23.15 hours. However, the master died of wounds despite untiring efforts to save his life by a doctor. All survivors were landed at Sheerness at 13.30 hours on 6 July.