Operation Transom

Operation Transom
Part of the South-East Asian theatre of World War II
Surabaya during the attack by Allied carrier aircraft on 17 May 1944
Date 17 May 1944 Location Surabaya, Netherlands East Indies 7°12′40″S 112°43′49″E / 7.211035°S 112.730260°E / -7.211035; 112.730260 Result Allied victory
Belligerents
United Kingdom  United States  Australia  France  Netherlands  New Zealand	Japan
Commanders and leaders
James Somerville
Strength
76 aircraft 2 aircraft carriers 3 battleships 1 battlecruiser 6 cruisers 14 destroyers 8 submarines	Anti-aircraft batteries
Casualties and losses
3 aircraft destroyed	Accounts differ
Unknown civilian casualties

Operation Transom was an attack by Allied forces against the Japanese-occupied city of Surabaya on the Indonesian island of Java during World War II. Conducted by the British-led Eastern Fleet, the operation took place on 17 May 1944 and involved American and British carrier-based aircraft bombing the city's docks and an oil refinery. An American torpedo bomber was shot down, and two British torpedo bombers were lost in accidents.

The attack on Surabaya was the second, and final, joint American-British aircraft carrier raid in the Indian Ocean during 1944. It was undertaken to divert Japanese forces from the Allied landing on Wakde island off New Guinea and make use of the American aircraft carrier on its return voyage to the Pacific. The warships involved in the operation sailed from Ceylon and refuelled in Western Australia before reaching the waters south of Java, where the carriers' aircraft were launched. On the morning of 17 May two groups of Allied aircraft made a coordinated attack on Surabaya's port and several industrial facilities that took the Japanese by surprise. American heavy bombers struck Surabaya that night and Australian aircraft laid mines in nearby waters; these aircraft operated from bases in northern Australia.

Estimates of the damage inflicted by the Allies differ. Some sources describe the results as modest, and others contend that they were significant. The number of civilian casualties caused by the raid is unknown. There is consensus that the operation provided the British Royal Navy with useful exposure to superior United States Navy carrier tactics. The attack had no effect on Japanese military deployments as the Eastern Fleet was not considered a serious threat.