The Attacker class were a class of escort aircraft carriers in service with the British Royal Navy during the Second World War.
Having already converted six diesel-powered C3 cargo ships into escort carriers (three of them becoming the British Avenger class), shortly after the Attack on Pearl Harbor the United States Navy earmarked 22 additional C3 vessels, these powered by steam turbines, for conversion into further carriers. While some classify all these ships, and 23 others, as members of the Bogue class, in fact the proper consisted only of eleven of the 22, which were retained by the U.S. Navy; while the remaining eleven were transferred to the Royal Navy under the terms of the Lend-Lease program, and were redesignated as the Attacker class. A number of British sources suggest that the three ships built by Seattle-Tacoma Shipbuilding--HMS Ravager, HMS Searcher, and HMS Tracker--should actually be considered part of the succeeding Ruler class, and not as Attackers; but in the absence of a clear consensus we will treat them as part of this class.
The ships were originally intended to serve as convoy escort carriers, equipped with both anti-submarine and fighter aircraft, and transport carriers, transferring new and replacement aircraft to forward bases. After successful use during the amphibious invasion of North Africa to cover advancing ground units until land airbases were secured, several ships were refit as strike carriers, equipped with just fighter aircraft. When used as convoy escorts, the ships' aircraft were successful in deterring German submarines from attacking Allied convoys, with a number of German submarines and aircraft destroyed or damaged by the aircraft. Those carriers operating in the strike role took part in two major landings in the Mediterranean and an operation against the in Norwegian waters. Eight of the ships ended the war in the Far East in the campaigns against the Japanese Empire and were then used to transport home prisoners of war.
All eleven ships survived the war and were eventually returned to the United States Navy, which sold eight of them for conversion back into merchant ships. The other three ships were scrapped.
Design and description The Attacker class vessels were all laid down in 1941 and 1942, with Ingalls Shipbuilding and Western Pipe & Steel building four each and Seattle-Tacoma Shipbuilding Corporation the remaining three. All were supplied to Britain under the terms of the Lend-Lease program.
The ships had a standard complement of 646 officers and ratings. Crew accommodations were significantly different from the normal for the Royal Navy at the time. Instead of food being prepared by separate messes, it was cooked in the galley and served cafeteria-style in a central dining area. As built, they were equipped with air conditioning, a modern laundry and a barber shop, and, in place of the hammocks found in Royal Navy ships, three-tier bunk beds, 18 to a cabin, which were hinged and could be folded up to provide extra space when not in use, were fitted. One source states that the laundry facilities and ice-cream-making equipment were removed before they entered service.
The ships had a waterline length of with an overall length of . Their beam was at the waterline and a maximum beam of . The draught was at full load and at light load. They displaced at standard load and at full load.
Power was provided by two Foster and Wheeler boilers feeding steam to a General Electric steam turbine engine connected to a single shaft, giving , which could propel the ship at .
All the escort carriers had the capacity for up to 20 anti-submarine or fighter aircraft, which could be a mixture of the British Hawker Sea Hurricane, Supermarine Seafire, and Fairey Swordfish, and the American Grumman Wildcat, Vought F4U Corsair and Grumman Avenger. The exact composition of the embarked squadrons depended upon the mission. Some squadrons were composite squadrons for convoy defence, and would be equipped with anti-submarine and fighter aircraft, while other squadrons working in a strike-carrier role would only be equipped with fighter aircraft. When utilised in ferry service the ships could carry up to 90 aircraft between both the flight and hangar decks. Aircraft facilities consisted of a small combined bridge–flight control island on the starboard side above the flight deck that measured . There were nine arresting wires and three barriers at the stern of the ship, along with one hydraulic catapult at the bow which was able to launch a aircraft at . The hangar deck was , which was larger than previous escort carriers, but retained the camber at the bow and stern of the main deck of the merchant ships they were built on. Because the elevators were placed at the ends of the flight deck, pulleys were required for handling planes on and off of the elevators on the hangar deck, which was difficult in normal conditions, and impossible in rough seas.
The ships were delivered with /51 calibre guns mounted on sponsons located on either side of the stern. Their anti-aircraft (AA) defence nominally consisted of eight Bofors AA guns in twin mounts, and eight Oerlikon AA cannon in twin and ten in single mounts as the standard fit. In practice all the ships had slightly different weapons mounted. Attacker, Chaser, and Hunter only had four single 20 mm AA cannon, the rest being double mounts. Of the other ships, Battler had two, Stalker had six, and Fencer had seven single 20 mm cannon. Pursuer had four extra 40 mm AA guns, and Striker had six extra in place of twin 20 mm mounts.
After arriving in Great Britain, the ships had their 5-inch guns changed out for 4-inch guns of a type which used British-made ammunition; sources differ as to what model of replacement gun was used, with the British-made BL 4-inch Mark IX (45-calibre) single-purpose (surface) gun or one of several marks of US-made, 4-inch/50 caliber gun (which had been supplied to Britain under Lend-Lease) among the suggestions. The ships had their aviation fuel capacity reduced drastically, in the interest of fire safety, from to , through the replacement of the original large, deep avgas tanks, within which vapors accumulated as they were emptied, with smaller ones which were topped off with seawater or CO2 as they were emptied, leaving no space for vapors to form. The smaller tanks could, in turn, be completely immersed in larger, water-filled enclosures, or encased in concrete, to further reduce the possibility of vapor accumulation, increasing safety further. HF/DF ("Huff/Duff") radio direction finders (RDF) were also installed at this time.
Service history + Construction data RN Name Name Builder Laid down Launched Commissioned Fate D02Steel Artisan Barnes (ACV-7) Western Pipe, San Francisco, California 17 April 1941 27 September 1941 10 October 1942 Returned 5 January 1946, later SS Castel Forte D18Mormacmail Altamaha (ACV-6) Ingalls Shipbuilding, Pascagoula, Mississippi 15 April 1941 4 April 1942 15 November 1942 Scrapped 1946–48 D32 Mormacgulf Breton (ACV-10) Ingalls Shipbuilding, Pascagoula, Mississippi 28 June 1941 15 January 1942 9 April 1943 Returned 12 May 1946, SS Aagtekerk D64 Croatan (ACV-14) Western Pipe, San Francisco, California 5 September 1941 4 April 1942 20 February 1943 Returned 11 December 1946, SS Sydney D80 Mormacpenn Block Island (ACV-8) Ingalls Shipbuilding, Pascagoula, Mississippi 15 May 1941 22 May 1942 11 January 1943 Returned 29 December 1946, SS Almdijk D73 Mormacland St. George (ACV-17) Ingalls Shipbuilding, Pascagoula, Mississippi 31 July 1941 18 July 1942 14 June 1943 Scrapped 1946–48 D70 ACV-24 Seattle-Tacoma Shipbuilding Corporation, Tacoma, Washington 11 April 1942 16 July 1942 25 April 1943 Sold into merchant service as SS Robin Trent. Scrapped in 1973. D40 ACV-22 Seattle-Tacoma Shipbuilding Corporation, Tacoma, Washington 20 February 1942 20 June 1942 7 April 1943 Sold into merchant service as SS Captain Theo. Scrapped in 1976. D91 Hamlin (ACV-14) Western Pipe, San Francisco, California 6 October 1941 5 March 1942 30 December 1943 Returned 29 December 1945, SS Riouw D12 Prince William (ACV-19) Western Pipe, San Francisco, California 15 December 1941 7 May 1942 29 April 1943 Scrapped 1946–48 D24Mormacmail BACV-6 Seattle-Tacoma Shipbuilding Corporation, Tacoma, Washington 3 November 1941 7 March 1942 31 January 1943 Sold into merchant service as SS Corrientes. Scrapped in 1964.
Convoy escorts
Escort carriers were designed to accompany other ships, forming the escort for convoys. The anti-submarine aircraft employed were initially Fairey Swordfish and later Grumman Avengers, which could be armed with torpedoes, depth charges, bombs, or the RP-3 rocket projectile. As well as carrying out their own attacks on U-boats, these aircraft identified target locations for the convoy's escorts to attack. Typically anti-submarine patrols would be flown between dawn and dusk. One aircraft would fly about ahead of the convoy, while another patrolled astern. Patrols would last between two and three hours, using both radar and visual observation in their search for U-boats. By 1944, it was usual to have two escort carriers working as a pair on convoy escort. Experience had shown it was best to have two composite squadrons. One squadron included fighters and the by then obsolete Fairey Swordfish equipped with air-to-surface vessel (ASV) radar for night patrols. The other squadron would be equipped with fighters and the Grumman Avenger for long-range day patrols, as they could not be fitted with the ASV radar.
The Fleet Air Arm squadrons flying off the Attacker-class escort carriers did have some successes of their own. The first of six confirmed U-boats destroyed by aircraft flying off Attacker class ships was on 10 February 1944, when two Fairey Swordfish from the 842 Naval Air Squadron on board sank west of Iceland. On 4 March, while on Arctic convoy patrol, Fairey Swordfish from 816 Naval Air Squadron on board so severely damaged with a salvo of RP-3 rockets that she could not submerge and was sunk by . For the rest of the day Chasers Fairey Swordfish kept the U-boats at bay by identifying their locations to her escorts. They also damaged two other U-boats themselves. The was sunk by RP-3 rockets fired from a Fairey Swordfish on 5 March, and the on 6 March. Three other U-boats sighted managed to evade an attack in foggy conditions. Operating from Fencer, 842 Squadron sank their second submarine, , on 1 May, and sank and on 2 May 1944.
The carriers' aircraft could also claim some success against the Luftwaffe's long-range bombers. On 1 December 1943, two Grumman Wildcats from 842 Naval Air Squadron on board Fencer shot down a Focke-Wulf Fw 200 that was shadowing Convoy OS 60. The next confirmed air-to-air success came on 24 February 1944, when four Grumman Wildcats from 881 Naval Air Squadron on board Pursuer were scrambled after the ship's radar had identified at least three aircraft approaching. The approaching bombers consisted of a mixed force of seven Focke-Wulf Fw 200 and Heinkel He 177s carrying glider bombs. One Fw 200 and one He 177 were shot down by Grumman Wildcats. The rest of the Germans kept their distance due to the combined efforts of the fighters and the ships' anti-aircraft fire. Off Cape Finisterre in March 1944, Grumman Wildcat fighters from Pursuer shot down a Heinkel He 177 and a Focke-Wulf Fw 200, and damaged a Fw 200.See also