The attack on Surabaya was the second, and final, joint American-British aircraft carrier raid in the Indian Ocean during 1944. It was undertaken as a diversion from the Allied landing on Wakde island off New Guinea on the same day, and to 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. The two groups of Allied aircraft that had been launched from the carriers were not detected by the Japanese before the raid commenced and made a well coordinated attack that was aided by good intelligence on the locations of key facilities in the city.