'Transom' was a British and US carrierborne air attack on Japanese targets at Soerabaja on the island of Java in the Japanese-occupied Netherlands East Indies (17/18 May 1944).
The undertaking was in effect a second iteration of the concept first tested in 'Cockpit'. On her arrival back in Ceylon on 27 April after 'Cockpit', the US fleet carrier Saratoga was ordered back to the USA for a major overhaul and refit, and Admiral Ernest J. King, the US chief of naval operations, suggested that with the support of Vice Admiral Sir James Somerville’s British Eastern Fleet she should strike at Soerabaja en route to the USA.
As Soerabaja is much closer to Australia than to Ceylon, the plan was to stage the raid from the Exmouth Gulf in Western Australia, and Somerville accordingly made arrangements to refuel his ships there. On 6 May the Eastern Fleet sailed from Ceylon: Somerville led Task Force 65 from Trincomalee with the battleships Queen Elizabeth, Valiant and Free French Richelieu, light cruisers Newcastle, Nigeria and Free Dutch Tromp, and destroyers Rotherham, Racehorse, Penn, Napier, Nepal, Quiberon, Quickmatch and Free Dutch Van Galen, while Vice Admiral Sir Arthur Power led TF66 from Colombo with the battle-cruiser Renown (transferred to TF65 on 7 May), Rear Admiral C. Moody’s fleet carriers Illustrious and Saratoga, light cruisers Ceylon and New Zealand Gambia, and destroyers Quilliam, Quadrant, Queenborough and US Cummings, Dunlap and Fanning.
On 30 April a support force had departed Trincomalee as Task Force 67 with a number of Royal Fleet Auxiliary vessels in the form of the Eagledale, Echodale, 8,296-ton Arndale, 5,892-ton Appleleaf, 5,911-ton Pearleaf and 5,150-ton Bacchus. Task Force 67 was escorted by the heavy cruiser London, destroyers Rotherham and Dutch Van Galen, and frigate Findhorn.
The ships of the two task forces refuelled on 15 May in Exmouth Bay from TF67, which comprised six fleet oilers, one water tanker and, as escort, the heavy cruisers London and Suffolk, which had departed Trincomalee on 30 April. The cruisers joined TF66 on 14 May.
Because he anticipated a stronger Japanese reaction on this occasion than in 'Cockpit', Somerville fixed the flying-off position at a distance of some 210 miles (340 km) from the target. As this was outside the tactical radius of the Fairey Barracuda attack warplane, Illustrious instead embarked Grumman Avenger machines.
The fleet sailed from Exmouth Gulf during the afternoon on 15 May and, once more undetected, arrived at the selected flying-off position, due south of Soerabaja, at 06.30 on 17 May, and by 07.20 had launched the attack force of 45 Avenger torpedo/level bombers and Douglas Dauntless dive-bombers, escorted by 40 Grumman Hellcat and Vought Corsair fighters. The attackers constituted two forces, one to attack an important oil refinery (the only source of aviation fuel in Java) and an engineering works, and the other to bomb the dockyard and shipping in the harbour. Despite the fact that the two forces had to fly overland for a considerable distance during their approach to Soerabaja, they encountered no Japanese fighters. Moreover, over the target area the Japanese anti-aircraft fire was light and generally ineffective.
The Allied aircraft achieved total surprise, and by 08.30 both attack forces had completed their attacks, which were undertaken simultaneously to divide the Japanese defences. The attack cost the Allies just one aeroplane, and destroyed 12 Japanese aircraft on the ground. The damage inflicted on the harbour installations and ships was greatly overestimated by the returning aircrews, however, and in fact only one 993-ton freighter and the patrol boat PB-36 had been damaged beyond repair, with lesser damage inflicted on the auxiliary submarine chasers Ch-107 and Ch-108, freighters Choka Maru and Tencha Maru, and tanker Yosei Maru.
Somerville later regretted that he did not repeat the attack in the afternoon, but as he was not flying his flag in a carrier he was unaware that some of the designated targets had been left undamaged in the harbour.
In addition, seven Consolidated B-24 Liberator land-based heavy bombers of the US 380th Bombardment Group made a follow-up night attack on Soerabaja harbour from the base at Corunna Downs Airfield in Western Australia.
On 18 May Saratoga and the three US destroyers separated from the Eastern Fleet, which had returned to Ceylon by 27 May.