Indian Ocean raid

The Indian Ocean raid (Operation C, the Third Mobile Operation in the Indian Ocean and the Battle of Ceylon in Japanese) was a sortie of the Imperial Japanese Navy (IJN) from 31 March to 10 April 1942. Japanese aircraft carriers (Admiral Chūichi Nagumo) struck Allied shipping, naval bases and airfields around British Ceylon but failed to find most of the Eastern Fleet. The British were forewarned by signals intelligence and the fleet sailed before the raid; its attempt to surprise the Japanese was frustrated by poor tactical intelligence. Concurrent with Operation C, the IJN dispatched Malaya Force (Vice Admiral Jisaburō Ozawa) consisting of the aircraft carrier Ryūjō, six cruisers, a light cruiser and four destroyers, to raid the northern Bay of Bengal. In three days, Malaya Force aircraft and ships sank twenty merchant ships and damaged three, a total of over 130,000 GRT. Following Operation C, the British expected a Japanese offensive in the Indian Ocean. The main base of the Eastern Fleet was moved to East Africa and Ceylon was reinforced. Somerville kept his fast carrier division, Force A, "in Indian waters, to be ready to deal with any attempt by the enemy to command those waters with light forces only". The Japanese had no plans to follow up their success and within the year, defeats in the Pacific made it impossible to do so.