HMS Archer was a Long Island-class escort carrier built by the United States in 1939–1940 and operated by the Royal Navy during World War II. She was built as the cargo ship Mormacland, but was converted to an escort carrier and renamed HMS Archer. Her transmission was a constant cause of problems which led to her being withdrawn from front-line service. She was used as a stores ship and then as an accommodation ship before a refit and subsequent use as a merchant aircraft ferry ship, Empire Lagan.

She was returned to the US Navy, then laid up as Archer before being sold into merchant service and converted to a passenger ship, Anna Salén. She was used to take emigrants to Australia and Canada in the early 1950s. She was sold and renamed Tasmania and after further service as an emigrant ship was converted back to a cargo ship. She was later sold and renamed Union Reliance. She was scrapped after a collision and fire in 1961.

Mormacland was laid down as a Type C3 cargo ship on 1 August 1939, under United States Maritime Commission contract (MC Hull 46), by the Sun Shipbuilding and Drydock Company, Chester, Pennsylvania, as Yard number 184. She was launched on 14 December 1939 and completed on 24 April 1940.

She was powered by four 2,225 bhp (1,659 kW) seven-cylinder two-stroke single-acting diesel engines. These drove a single screw via Westinghouse electro-magnetic slip couplings and Falk single reduction gears. The engines were built by Busch-Sulzer Brothers Diesel Engine Co, St Louis, Missouri with 20½ inches bore and 27 inches stroke (520 mm by 690 mm). They developed a total of 2,060 horsepower (1,540 kW) each. As HMS Archer, she had a range of 14,550 nautical miles (26,950 km) at 10 knots (19 km/h). The propulsion system was also used on the four sister ships built by Sun Shipbuilding in 1939: Mormacpenn, Mormacyork, Mormacland and Mormacmail

HMS Archer was the only Long Island-class escort carrier in service with the Royal Navy during the Second World War. She was converted from the American merchant ship Mormacland which was built at the Sun Shipbuilding and Drydock Company. She was laid down on 1 August 1939, launched on 14 December 1939 and delivered on 24 April 1940.

She was converted to an escort aircraft carrier at Newport News Shipbuilding & Drydock Co, Newport News, Virginia and commissioned into the Royal Navy on 17 November 1941.

Archer had a complement of 555 men and an overall length of 492.25 feet (150.04 m), a beam of 66.25 feet (20.19 m) and a height of 23.25 ft (7.09 m). She displaced 8,200 long tons (8,332 t) at normal load and 9,000 long tons (9,144 t) at deep load. Propulsion was provided by four diesel engines connected to one shaft giving 8,500 brake horsepower (6,300 kW), which could propel the ship at 16.5 knots (30.6 km/h; 19.0 mph).

Aircraft facilities were a small combined bridge–flight control on the starboard side and above the 410-foot (120 m)-long wooden flight deck, one aircraft lift 43 by 34 feet (13 by 10 m), one aircraft catapult and nine arrestor wires. Aircraft could be housed in the 190 by 47 feet (58 by 14 m) half hangar below the flight deck. Armament comprised three single mounted 4-inch dual purpose anti-aircraft guns and fifteen 20 mm cannons on single or twin mounts. She had the capacity for fifteen aircraft which could be a mixture of Grumman Martlet or Hawker Sea Hurricane fighter aircraft and Fairey Swordfish or Grumman Avenger anti-submarine aircraft.