Indian Ocean Raid - First Moves

First Moves

Following the destruction of the American-British-Dutch-Australian Command forces in the battles around Java in February and March, the Japanese sortied into the Indian Ocean to destroy British seapower there and support the invasion of Burma. The Japanese force, commanded by Admiral Chuichi Nagumo, had six carriers: Akagi, Ryūjō, Hiryū, Sōryū, Shōkaku, and Zuikaku. This powerful force left Staring Bay, Celebes on 26 March 1942.

Signal decrypts provided the British commander of the Eastern Fleet, Vice Admiral Sir James Somerville with warning of the Japanese sortie, and he retreated to Addu Atoll in the Maldive Islands, expecting an attack on 1 or 2 April.

The first raids were against shipping in the Bay of Bengal by the carrier Ryūjō and six cruisers under the command of Admiral Jisaburo Ozawa. They sank 23 ships. Five more were sunk by submarines off India's west coast.

When the expected attack on Ceylon failed to take place, Somerville sent the slow carrier HMS Hermes back to Trincomalee for repairs, escorted by the heavy cruisers HMS Cornwall and Dorsetshire, and the Australian destroyer HMAS Vampire.

On the evening of 4 April, the Japanese fleet was detected 400 mi (350 nmi; 640 km) south of Ceylon (Sri Lanka) by a PBY Catalina flown by Squadron Leader Leonard Birchall of 413 Squadron, Royal Canadian Air Force. The location of the fleet was transmitted before the Catalina was shot down by a A6M2 Zero fighter from Hiryū.