At 08.15 hours on 15 Oct, 1941, U-553 torpedoed and sank the Silvercedar in convoy SC-48 and missed at 08.17 hours another ship and thought that she had hit a ship beyond, but this was not the case. At 08.23 hours, U-553 fired two torpedoes and sank the Ila.

The Ila (Master Thore K. Johnsen) was struck at the #2 hatch and under the east side of the bridge. The explosions broke the ship in two, causing her to sink immediately. No lifeboats were launched, because one was destroyed and the other jammed under a davit. Six men, including the master kept themselves afloat on wreckage, while the first mate, first engineer and two crewmen held to the capsized motor lifeboat, but the first engineer soon died of the cold and exhaustion and slid off. The survivors drifted for three hours until they were picked up at dawn by the corvette FFL Mimosa (J 6254) (Capt Roger Birot) but the third engineer and an able seaman died shortly thereafter on board.