At 00.01 hours on 17 July 1943 the unescorted City of Canton (Master Edward Scrymgeour) was hit by one of two G7a torpedoes from U-178 northeast of Beira. The U-boat had chased the ship since 18 hours, almost loosing her in a rain squall and missing with a spread of two G7e torpedoes at 15.26 hours on 16 July. 15 minutes after the hit a first coup de grâce was fired which malfunctioned, but a second hit amidships at 00.31 hours and caused the ship to sink after breaking in two. The Germans questioned the survivors in two lifeboats and took the second officer Reginald Marry Broadbent as prisoner aboard, because the master could not be found.

Seven crew members of the 82 crew members and eleven gunners aboard were lost. Most survivors made landfall in two lifeboats near Pinta lighthouse in Portuguese East Africa. Twelve survivors were picked up by the Portuguese steam passenger ship Luabo and landed in Almino. The master and one crew member were picked up from a raft by FFL Suffren and landed at Durban on 26 July.