etween 1918 and 1940 the Admiralty concentrated on the development of aircraft carriers capable of supporting the battle fleet in action, and opposition from the RAF had made it difficult to equip and man even the modest force that was created. Some attention was given to trade protection, but Coastal Command of the RAF had responsibility for operations to detect and attack hostile shipping in European waters and active sonar, known originally as Asdic, was believed to have given escorts the edge against submarines. In the 1914-18 war most U-boat operations had been confined to coastal waters, and even after Nazi Germany was perceived as a threat in the mid-1930s it was by no means obvious that, in the event of war, a new generation of U-boats could break through the Coastal Command ‘barrier’ to operate in the open ocean. Surface raiders were seen as a greater threat, and these would be contained by the battle fleet and detached forces created for the purpose, which could include aircraft carriers.
Technical background
The Admiralty showed some interest in trade protection carriers in 1936, but came to the conclusion that there were insufficient funds to build, equip and operate such ships in the peacetime fleet.
Despite this, DNC was tasked to produce sketch designs for conversions that could be taken forward in an emergency; these included the Union Castle liner Winchester Castle of 20,109 tons, completed in 1930, and the Shaw, Savill Line Waipawa of 12,500 tons, completed in 1934. The pressure of rearmament work prevented any detailed drawings being prepared, but the genesis of the concept of converting suitable merchant ships into utilitarian carriers for tasks unconnected with main fleets survived. ‘Auxiliary aircraft carriers’, as they were termed, appeared on the agenda of conferences held in 1937 and 1938 to discuss the protection of seaborne trade in the war that appeared increasingly likely, but they were rejected on both occasions on the basis that merchant shipping was required for ‘other more important services’. Even the outbreak of war in 1939 failed to change this view, since ‘auxiliary carrier’ conversions were expected to take a year or more to convert using scarce shipbuilding resources, and the Ministry of War Transport refused to allocate merchant ships for the purpose. Initially the war followed the anticipated pattern. Cruisers were formed into hunting groups, some of them with carriers, to search the oceans for German raiders, but the 1939 ‘Fighting Instructions’ failed to see the need for control of the third dimension over convoys and stated that
‘small escort forces and evasion can be relied upon to provide sufficient security during the ocean passage’. Coastal Command and local flotillas were to augment the close escort in the littoral danger areas approaching ports. However, the fall of Norway and France in the summer of 1940 changed the picture dramatically. Germany’s U-boats could range far out into the Atlantic from bases such as Lorient, unlike their First World War predecessors, and attack convoys where their ocean escorts were minimal and Coastal Command could not reach. Aircraft such as the Focke-Wulf Fw 200s of KG40 could locate convoys without opposition, especially those heading for Gibraltar and in the
eastern Atlantic, and attack them with bombs. Desperate measures were taken to counter this air threat, including fighter catapult ships manned by the RN, with a handful of fighters that could be launched by catapult but not recovered, and catapult-armed merchants ships or CAM-Ships. The latter were cargo-carrying merchant ships fitted with a single RAF-manned Hurricane fighter on a catapult fitted over the bow. If launched out of range of land, the fighter had to be ditched near the convoy, with the certain loss of the aircraft and the possible loss of the pilot. This led to an understandable reluctance to launch in any but the most ideal circumstances.
A starboard bow view of Campania. (RAN VIA JOHN PERRYMAN)
In the autumn of 1940 Captain Mathew Slattery RN, the Director of Air Material at the Admiralty, proposed fitting the simplest possible flight deck and arrester wires on to suitable merchant hulls so that they could launch fighters in defence of convoys and, critically, recover them after combat. The Ministry of War Transport still refused to allow merchant ships to be taken up from trade for the purpose but, after Prime Minister Winston Churchill’s ‘Atlantic Directive’, agreed that ships already under Admiralty control could be used. Steps to convert the first operational escort carrier followed.
The Admiralty subsequently drew up a table of features to be taken into account in ships considered for conversion, including size, speed and propulsion. Three broad classes were designated A, B and C, the first having the best features and the last being the most austere.
Because the RN had too few fleet carriers, the Admiralty saw the new escort carriers as general- purpose vessels capable of a wide range of tasks. Some were fitted as ‘assault’ carriers capable of operating fighters in support of amphibious operations. Others were fitted for antisubmarine operations, and both received British radars and sophisticated operations rooms capable of bringing together information from a wide range of sensors and ‘fusing’ it to build up a tactical picture for the command.
Following Captain Slattery’s proposal, a captured German merchant ship renamed Empire Audacity and originally intended for use as an ocean boarding vessel was allocated for conversion into an auxiliary aircraft carrier, and work was completed in six months. The bridge, funnel and masts were removed and a flight deck built over the accommodation structure amidships. Unlike previous British aircraft carriers, the flight deck was a lightweight superstructure and incorporated expansion joints. The space between the hull and the flight deck was partly plated-in aft, but there was no hangar and therefore no need for a lift, and no workshops. The exhaust from the single diesel engine was led out through new trunking to starboard below flight-deck level, and platforms were fitted to port and
starboard about 100ft aft of the bow for ship control and visual signalling. They were about 4ft below flight-deck level and joined by a cross-connecting passageway under the flight deck. These positions offered only a limited arc of visibility to the officer conning the ship. Little could be seen to port from the starboard position, for instance, and the captain was known to be unhappy about operating inside the convoy at night as a consequence. This may have contributed to his decision to remain outside the convoy and, ultimately, to the ship’s loss. The installation of an island from which the ship could be adequately controlled in close proximity to other vessels was considered to be an essential development for subsequent types of escort carrier. A single mast was stepped by the starboard conning position. Windbreaks were fitted to the side of the deck aft which could be pulled up to provide some protection for the aircraft against the elements, but all maintenance, refuelling and rearming had to be carried out on deck. A single 4in gun and several close-range weapons were fitted. Aircraft maintenance personnel used portable outfits of tools and spare parts.
Audacity seen from the starboard beam, with a CAM -Ship in the background. The aircraft ranged aft are M artlets of 802 NAS, partly protected against the elements by the windbreaks. (AUTHOR’S COLLECTION)
In view of the limited engineering facilities on board, a special, simplified arrester gear system was installed capable of stopping a 9,000lb aircraft at an entry speed of 55 knots relative to the deck.
The work to produce the gear was justified by the expectation that a number of mercantile conversions would follow. There was some discussion about the number and type of aircraft she would embark, and a mixture of fighters and Swordfish was considered, but an all-fighter air group was eventually chosen, to offset the lack of air-defence capability in escort groups. The American- built Grumman Martlet was chosen as the most robust carrier fighter available at the time, and the only one available to the RN that had been designed for operation at sea. Since her machinery was of a type with which the RN was not familiar, most of Audacity’s technical sailors came from the Merchant Navy, serving with the RN under T.142X articles. Pilots were accommodated in the former passenger cabins, and very little of the ship below the flight deck was altered.
Although it is of poor quality, this image does show how the M artlets had to be ‘herring-boned’ in the range to fit on the narrow flight deck. The single barrier is rigged fairly well forward by the pole mast. (AUTHOR’S COLLECTION)
There was just enough space on the flight deck to range six Martlets in a ‘herring-bone’ pattern aft, leaving just enough space for the furthest forward to carry out a free take-off. There were two arrester wires, a third ‘safety’ wire and a single barrier. An aircraft that engaged the safety wire was likely to engage the barrier, but at a reduced speed which would cause less damage. Aircraft were usually launched in sections of two, and for recoveries the aircraft on deck were pushed by hand forward of the barrier, and then aft into the range again when it was complete. The aircraft were not flown at night, and, since the ship operated fully darkened, maintenance to prepare for dawn launches had to be carried out by dim torchlight. Aircraft ammunition and avgas were stowed in the former holds, the latter meeting the usual RN safety standards, which reduced the amount that could be carried.
To offer effective air defence of a convoy with her limited number of fighters, it was essential that Audacity was fitted with radar, and during her conversion she received the second prototype Type 79B ‘single-masted’ air warning set. This carried both transmitter and receiver on the same mast and was fitted at the very top of the single pole-mast just aft of the starboard conning position. Her fighter direction officer was an RNVR former Cambridge don who had just taken part in the first course at the new fighter direction school at RNAS Yeovilton. He was promoted and awarded the MBE for his services.
Initially she retained the name Empire Audacity and was referred to as an ‘auxiliary aircraft carrier’, but it was soon learnt that senior officers failed to recognise the ship as an operational aircraft carrier, especially since the name prefix ‘Empire’ was usually applied to merchant ships in government service and the term ‘auxiliary’ was usually applied to fleet support ships such as tankers and stores vessels. The misunderstanding was resolved by changing her name to Audacity and referring to her as an escort aircraft carrier. Stability was affected by the ship’s lightened structure, and she was fitted with 3,000 tons of ballast during the conversion.
Audacity technical details
Displacement: 11,000 tons deep load
Dimensions:
length 467ft 3in beam 56ft 3in draught 21ft 7in
Machinery: 1 shaft Vulkan diesel
5,200bhp delivering 14½ knots Armament:
1 x 4in HA; 1 x 6pdr; 4 x single 2pdr ‘pom-pom’; 4 x
single 20mm Oerlikon
Fuel: 649 tons diesel
Endurance: 12,000 miles at 14 knots
Complement: 210
Aircraft operating data
Flight deck: 453ft x 60ft steel plate
Arrester wires: 2 x 9,000lb at 55 knots; 1 x 9,000lb at 55 knots ‘safety wire’;1 barrier 9,000lb at 55 knots with 40ft pull-out Aircraft: Up to 8
Aircraft fuel: 10,000gal avgas
Air weapons: 0.5in gun ammunition; flares and pyrotechnics
Audacity operational history
The cargo liner Hannover was completed by the German shipbuilder Vulkan in Bremen on 10 May 1939 and put into commercial service with the Nordeutscher-Lloyd Line for trade with the West Indies. She was captured by the cruiser Dunedin and the Canadian destroyer Assiniboine while trying to evade the British blockade in March 1940, and converted initially for use as an ocean boarding vessel, renamed Empire Audacity. In January 1941 she was taken in hand by the Blyth Drydock and Shipbuilding Company in Northumberland for conversion into an escort carrier. The work was completed in June and she was commissioned as Empire Audacity on 20 June 1941, sailing for trials in the Clyde soon afterwards. On 10 July a Martlet of 802 NAS was the first aircraft to land on her deck, and on 31 July she was renamed Audacity.
After a work-up she sailed as part of the escort for convoy OG74 to Gibraltar on 13 September, during which her aircraft shot down one Fw 200 and sighted a U-boat. She returned to the UK with convoy HG74, which was unopposed. On 29 October she sailed from the Clyde as part of the escort for convoy OG 76 to Gibraltar. In the next ten days her Martlets shot down two Fw 200s and chased off a third. On 14 December 1941 she sailed with the escort for HG76, the return convoy to the UK, in what was to prove her last action. Although 802 NAS had only four serviceable fighters left, in six flying days they shot down two Fw 200s, damaged three more and chased off a further three. They also sighted or assisted surface escorts in the destruction of eight U-boats in one of the most decisive convoy actions of the war.
Unfortunately, on the night of 21 December 1941 Audacity was left outside the convoy screen without her own escort. She was hit by a torpedo from U-751, which flooded the engine room, stopped her and caused her to settle by the stern. A surfaced U-boat was seen on the port side and she engaged it with P1 and P2 ‘pom-poms’ before being hit by two more torpedoes which caused her to sink at 2210, bows first, 10 miles to starboard of HG76 in position 43 45N 19 54W. Her short but brilliant career had shown the escort carrier to be a vital component of convoy defence, and immediate steps were made to increase the number being made available by the USN. The Ministry of War Transport withdrew its opposition to suitable merchant ships being converted, and the next was Activity.
Audacity’s success led to urgent studies to provide more escort carriers, including orders for ships to be built in the USA, which will be described in a later chapter. The conversion of Winchester Castle was reconsidered, but by 1941 she was too valuable as a troopship. New
construction was considered to be too time-consuming, and there was insufficient capacity for it in the UK, but one suitable hull under construction was identified. This was the diesel-powered, fast refrigerated transport Telemachus, building in Dundee for the Ocean Steam Ship Line. She was requisitioned in January 1942 and converted over the next ten months as an ‘improved Audacity’. As in other escort carriers, the ship’s company technical staff was largely made up by merchant navy sailors serving under T.142X articles.
The principal improvements were a small hangar aft capable of holding six folded Swordfish and served by a single lift; a small island on the starboard side forward of amidships from which ship and flying control were exercised, aft of which there was a pole mast for her Type 79B air and Type 272 surface warning radars and ‘YE’ aircraft homing beacon. A second control position at flight-deck level was sited to port, level with the island, for signalling, and limited ship control when appropriate; a cross-passage under the flight deck linked the two. Basic workshops were fitted forward of the hangar. The designed aircraft complement was three Swordfish and seven Martlets, to be operated by a single, composite naval air squadron. The avgas stowage was doubled while still meeting RN standards of safety, and the hangar was fully enclosed in the normal British practice, only accessible via the lift or air-locks.
While she represented a considerable advance on Audacity, she was considerably less capable than contemporary American escort carriers, and this limited her usefulness. The single lift meant that it was sometimes necessary to range a number of aircraft to get at a serviceable machine if it was
‘blocked in’ at the forward end of the hangar. The limited avgas supply could pose problems on prolonged convoy operations, but on the other hand her riveted hull was thought to be more robust in rough, northern seas than the welded hulls of her American contemporaries. She had to keep some aircraft in a deck park as not all could be struck down into the hangar, and windbreaks could be raised around the after part of the flight deck to protect the range. The ship’s sides were plated in up to flight-deck level in order to improve her sea-keeping qualities in rough weather.
Activity technical details
Displacement: 14,250 tons deep load Dimensions:
length 512ft beam 66ft 6in draught 25ft 1in
Machinery: 2-shaft Burmeister & Wain diesels 12,000bhp delivering 18 knots Armament:
1 x twin 4in; 6 x twin 20mm Oerlikon; 8 single 20mm Oerlikon
Fuel: 2,000 tons diesel
Endurance: 4,500 miles at 18 knots
Complement: 700
Aircraft operating data
Flight deck: 498ft x 66ft steel plate Hangar: 87ft x 59ft x 21ft Arrester
wires:
2 x 15,500lb at 60 knots; 2 x 15,500lb at 55 knots; 1 x 15,500lb at 55 knots ‘safety wire’; 1 barrier 15,500lb at 55knots with 40ft pull-out
Lift: 42ft long x 20ft wide Aircraft: Up to 15