Operation Cockpit

'Cockpit' was a British carrierborne air attack on Sabang island off the north coast of Sumatra in the Japanese-occupied Netherlands East Indies (19 April 1944).

From the middle of 1942 until a time early in 1944 the Allies undertook no offensive naval operations in the Indian Ocean. Their main naval force in the region, Admiral Sir James Somerville’s Eastern Fleet, was weak. From January 1943 the fleet included no aircraft carriers and its three elderly battleships were transferred later in the year, leaving the Eastern Fleet with a strength capable only of protecting Allied shipping. Fortunately for the Allies, the Japanese did not attempt any major operations in the Indian Ocean, and this made it possible for the Eastern Fleet to focus on countering German and Japanese submarines and using its own submarines to raid Japanese shipping.

At the 'Sextant' conference held during November 1943 in Cairo, the Allied leadership agreed that 'the main effort against Japan should be made in the Pacific', and that the Indian Ocean would be a subsidiary theatre. It was also decided that any offensive operations, including carrier raids, in the theatre would have the goals of 'maintaining pressure on the enemy, forcing dispersion of his forces, and attaining the maximum attrition of his air and naval forces and shipping'.

In January 1944, the Admiralty decided to undertake a substantial reinforcement the Eastern Fleet. This had been made possible by the surrender of the Italian navy in 1943, which removed one of the Royal Navy’s main opponents and gave the Allies control over the Mediterranean Sea. The reinforcements which were scheduled to arrive over the next four months comprised 146 warships, and included three battleships, two aircraft carriers, 14 cruisers and large numbers of destroyers and other escort vessels. The first substantial group of reinforcements reached the Eastern Fleet’s base in Ceylon on 27 January: these included the aircraft carrier Illustrious, the battleships Queen Elizabeth and Valiant and the battle-cruiser Renown. An overall shortage of destroyers hindered the fleet’s ability to conduct offensive operations until April, however, as priority needed to be given to escorting convoys.

Moreover, early in 1944 the Japanese transferred its main naval striking force, the Admiral Mineichi Koga’s Combined Fleet, to Singapore. This was done to shift the fleet’s main strength from its current bases in the central Pacific, which were now vulnerable to US attacks, and concentrate it at a location with good naval repair facilities and ready access to fuel. Despite Singapore’s location near the eastern side of the Indian Ocean, the Japanese did not intend to make any large-scale incursions into these waters. The Allies were concerned about the Combined Fleet's intentions, however, and Somerville believed that his force would be unable to counter the Combined Fleet should it enter the Indian Ocean. As a result, additional Allied air units were despatched to protect Ceylon. The US Navy also agreed to the temporary transfer of the fleet carrier Saratoga and three destroyers from the Pacific to augment the Eastern Fleet: this was done so that the British did not have to find reinforcements for the Eastern Fleet by cancelling the planned 'Tungsten' carrier raid on the German battleship Tirpitz in Norwegian waters.

By March 1944 the British had five naval air stations in Ceylon and southern India, and these were capable of supporting 34 Fleet Air Arm squadrons and possessed the maintenance and repair facilities sufficient to handle 400 aircraft. The possibility of farther-flung operations was constrained, however, by the fact that the Eastern Fleet had only one fleet carrier, Illustrious, for as noted above, the departure of Victorious from Admiral Sir Bruce Fraser’s Home Fleet had been delayed to enable her to take part in the attacks on Tirpitz, and the ship was now due to arrive only in July. Somerville was also scheduled to receive the fleet carriers Indomitable and Formidable in due course.

In the meantime, and also as noted above, the Eastern Fleet’s carrier strength was to be boosted by the loan of the US Saratoga, which was on her way from the Pacific by way of Australia. In March two British escort carriers, Shah and Begum, also joined the Eastern Fleet. Another addition was a number of long-range escorts for convoy protection, which made it possible for some of the Eastern Fleet’s destroyers to be returned to their primary task of escorting the larger warships.

On 21 March the battleships Queen Elizabeth and Valiant, the battle-cruiser Renown, the carrier Illustrious, four cruisers and 10 destroyers departed Ceylon to sweep the maritime route linking Australia and the Middle East, which had recently been raided by a Japanese cruiser force, and to meet Saratoga. The main goals of this 'Diplomat' operation were to search for Japanese ships following an unsuccessful cruiser raid and to link with Saratoga. The operation also provided an opportunity to practise operating the ships together and refuelling at sea ahead of the start of the fleet’s planned offensive operations. After departing Ceylon, the British ships refuelled from tankers between 24 and 26 March and made rendezvous with Saratoga and her three escorting destroyers on 27 March. The carriers' aircraft exercised together during the return voyage, and the fleet arrived back at Ceylon on 2 April.

The decision to attack Sabang was made in response to a request from the US Navy’s chief of operations, Admiral Ernest J. King. King asked that the Eastern Fleet undertake a raid during the middle of April to prevent the Japanese from despatching naval aircraft stationed in southern Malaya to attack the large Allied naval forces allocated to the 'Reckless' amphibious landings at Hollandia on the northern coast of New Guinea on 22 April. At a meeting on 12 April, the Eastern Fleet’s senior officers decided to conduct a carrier raid on Sabang. The plans for the operation also included a surface ship bombardment of Sabang, but shortly before the fleet’s departure it was decided to omit this latter as it was believed that an undertaking so close to the shore would be unduly risky. The raid was considered to be a trial, to test the fleet’s procedures ahead of more ambitious operations. During the first two weeks of April, the Eastern Fleet finalised its plans for the attack and rehearsed the operation, which was to be the first aircraft carrier raid attempted by the Eastern Fleet.

The island of Sabang lies off the north-western tip of Sumatra, and had come into service as a base for the Imperial Japanese navy during the Japanese operations to seize the Dutch East Indies. Its location at the northern entrance of the Strait of Malacca made it strategically important. The Imperial Japanese navy’s 9th Base Force was the main unit stationed at Sabang, and from February 1944 this force was commanded by Rear Admiral Hirose Sueto. The British believed that the island’s garrison comprised some 9,000 men.

The Allies had little real intelligence on the Japanese forces at Sabang, their estimates being derived largely from small numbers of aerial reconnaissance photographs. It was believed that the island was strongly defended, and that the Japanese had sited a radar station and an airfield there. Somerville decided against further reconnaissance flights over the island for fear that these would alert the Japanese. However, intelligence gained from decryption of German and Japanese coded radio traffic contributed to the planning of 'Cockpit' by allowing the Allies to track the locations of Japanese warships and air units in the region. The Far East Combined Bureau also developed a radio deception plan for the operation which proved successful.

Despite the Allied fears, the Japanese had little interest in engaging the Eastern Fleet. The Imperial Japanese navy was aware that the fleet was too weak to pose a significant threat, and was therefore more concerned with the preservation of its own forces, including the warplanes in southern Malaya, with which to contest the US advance through the central Pacific. The Combined Fleet was under orders to engage the Eastern Fleet only in the event that the latter mounted a major attack. Land based naval bombers were assigned to counter Allied naval forces in the Indian Ocean.

On the orders of Admiral the Lord Louis Mountbatten’s South-East Asia Command, Somerville now prepared the 'Cockpit' carrierborne air attack on Sabang. At this time, the Japanese forces in Burma were under pressure and suffering serious supply problems: the raid was expected to exacerbate these problems and thereby assist Lieutenant General Sir William Slim’s British 14th Army. A further gain was the opportunity for Royal Navy and Fleet Air Arm crews to work with US Navy personnel and learn procedures needed for their subsequent deployment as part of what was to be Fraser’s British Pacific Fleet. However, King’s request for the Eastern Fleet to carry out a diversionary raid in the Indian Ocean caused a postponement.

At this time the Japanese knew that the Eastern Fleet lacked the strength to offer a serious challenge to their position in South-East Asia, and also discounted the threat of any large-scale seaborne offensive. They clearly perceived the Pacific to be the decisive theatre, as is indicated by an order issued by Koga, the commander of the Combined Fleet, on 8 March: 'The Combined Fleet is currently directing its main operations to the Pacific, where it will bring to bear the maximum strength of all our forces to meet and destroy the enemy, and to maintain our hold on vital areas. If during these operations a strong enemy attack takes place in South-East Asia, and with the situation in the Pacific permitting, air reinforcements will be sent so that the occupation force and enemy fleet will be destroyed. Consideration must be given to ensure that this diversion of strength shall not gravely impede the disposition of forces for a decisive battle in the central Pacific.'

Koga was killed when his aeroplane disappeared at sea on 31 March, but his successor, Admiral Soemu Toyoda, maintained the policy.

On 16 April the Eastern Fleet departed Trincomalee with Somerville flying his flag in Queen Elizabeth. The Eastern Fleet was at this juncture an Allied formation as it comprised Somerville’s own Task Force 69 (the battleships Queen Elizabeth, Valiant and Free French Richelieu, the light cruisers Newcastle, Nigeria, Ceylon, New Zealand Gambia and Free Dutch Tromp of Rear Admiral A. D. Reid’s 4th Cruiser Squadron, and the destroyers Rotherham, Racehorse, Penn and Petard, Australian Quiberon, Napier, Nepal and Nizam and Free Dutch Van Galen), and Vice Admiral A. J. Power’s Task Force 70 (the battle-cruiser Renown, the fleet carriers Illustrious and US Saratoga under the tactical command of Rear Admiral C. Moody, the heavy cruiser London, and the destroyers Quadrant, Quilliam and Queenborough, and US Cummings, Dunlap and Fanning). The submarine Tactician was also stationed near Sabang to rescue any airmen who were forced down during the attack. This was the largest force the Eastern Fleet had been able to send into combat up to that point in the war.

Each carrier had an air group made up of units from their parent navies. Illustrious embarked two squadrons equipped with 14 Vought Corsair single-engined fighter-bombers each and two squadrons operating a total of 21 Fairey Barracuda single-engined torpedo and dive-bombers. Saratoga's air group comprised one squadron of 26 Grumman F6F Hellcat single-engined fighters, one squadron of 24 Douglas SBD Dauntless single-engined dive-bombers and one squadron of 18 Grumman TBF Avenger single-engined torpedo-bombers, as well as a single Hellcat allocated to the air group’s commanding officer, Commander Joseph C. Clifton, who led both carriers' air wings.

After an uneventful passage, and without being detected by the Japanese, the Allied force arrived at the carriers' flying-off point some 100 miles (160 km) to the south-west of Sabang in the early hours of 19 April. The launch of the attack force began at 05.30: Illustrious despatched 17 Barracuda and 13 Corsair aircraft, and Saratoga 24 Hellcat, 18 Dauntless and 11 Avenger aircraft. Of the Hellcat machines, 16 were to escort the attack force and eight were to attack Lho Nga airfield in northern Sumatra. A combat air patrol comprising four Corsair and eight Hellcat fighters was maintained over the fleet.

The attack on Sabang began at 07.00. Saratoga's aircraft arrived over the island at that time, and Illustrious's aircraft began their attack from a different direction just one minute later. The Allied bombers mainly attacked oil storage tanks, shipping and harbour installations. The fighters struck Sabang’s airfield and Lho Nga airfield. Three of Sabang’s four oil tanks were set on fire and the harbour installations were badly damaged. Few ships were in the area, though a merchant vessel was sunk and another driven aground. The fighter pilots claimed to have destroyed 21 Japanese aircraft at Sabang airfield and another three at Lho Nga. The British pilots failed to engage a number of worthwhile targets of opportunity.

The Japanese at Sabang were taken by surprise, and their anti-aircraft batteries began to fire on the Allied aircraft only after the attack had started, and no Japanese fighters were encountered in the air. One Hellcat was shot down, and its pilot was rescued by Tactician while under fire from coastal artillery. Clifton led a group of fighters which drove off a Japanese torpedo boat that was threatening the submarine during the rescue. Some 11 other US aircraft were damaged.

As the Allied fleet withdrew after recovering its aircraft, it was approached by three Mitsubishi G4M 'Betty' torpedo bombers, all of which were shot down by Hellcat fighters at a location about 50 miles (80 km) to the north-east of the ships. Allied warships fired on Japanese aircraft twice during the night of 19/20 April. Some of the destroyers also fired at what turned out to be an Allied Douglas C-47 Skytrain twin-engined transport aeroplane which was flying from Cocos island with its identification friend or foe system turned off. During a rain squall in the afternoon of 20 April, Renown mistook the Australian destroyer Nepal for a Japanese vessel and briefly engaged her with her secondary armament. The attack force returned to Ceylon on 21 April.

The Allies were generally satisfied with the results of 'Cockpit'. While the operation had not inflicted heavy casualties on the Japanese, the Royal Navy had learned useful lessons. In particular, the British were impressed with the more efficient manner in which Saratoga's crew managed flight operations. However, the attack had no effect on Japan’s military strategy or deployments. The aircraft in southern Malaya remained there, and no changes were made to the plans to resist the Allied landings at Hollandia.

Shortly after the attack force had returned to Ceylon, Saratoga received orders to return to the USA for a refit. On King’s suggestion, she and most of the other ships involved in 'Cockpit' conducted an attack on Soerabaya, on the south coast of Java, on her return journey. This 'Transom' raid was undertaken on 17 May. The Eastern Fleet made several other carrier raids during 1944, including 'Crimson' as a second attack on Sabang on 25 July. This operation involved two British aircraft carriers, and included a battleship bombardment of the island.