launched as American motor merchant Rio Hudson for Mooremack South America Line Inc, New York. In July 1941, delivered incomplete for conversion to the escort carrier USS Avenger (CVE 2), fitted with 15 aircraft.
On 26 Dec, 1941 sold to the Royal Navy and commissioned as HMS Avenger (D 14).

At 09.54 hours on 13 Sep, 1942, U-589 (Horrer) attacked the convoy PQ-18 in grid AB 2566 and reported one ship with 7000 grt sunk. At 09.55 hours, a spread of two torpedoes was fired at the HMS Avenger (D 14) and after 3 minutes 35 seconds two detonations were heard. It is likely that U-589 made her claims as a result of hearing detonations caused by U-408 (von Hymmen), which was attacking the PQ-18 almost simultaneously. 

At 04.14 hours on 15 Nov, 1942, U-155 fired a spread of four torpedoes at the convoy MKF-1Y about 120 miles northwest of Gibraltar and heard three detonations, but was not able to made visual observations. The Ettrick and the HMS Avenger (D 14) were sunk and the USS Almaack (AK 27) was damaged.

The HMS Avenger (D 14) (Capt Colthurst) was hit by one torpedo, which ignited her bomb load and blew out the centre section of the ship. She sank within two minutes. The survivors were rescued by the Norwegian destroyer HNoMS Glaisdale (L 44) - further search for more survivors proved fruitless.