Indian Ocean raid

Indian Ocean raid. Having incapacitated the US Pacific Fleet at Pearl Harbor and supported the invasions of New Britain and the Netherlands East Indies, Vice-Admiral Nagumo's carrier striking force sailed into the Indian Ocean in March 1942 to attack Ceylon (see Map 51). Opposing this Japanese incursion was Admiral Somerville's British Eastern Fleet, which included five elderly battleships, three carriers, and five cruisers. While Nagumo mounted bombing raids on the island with his aircraft, Vice-Admiral Ozawa led a smaller number of ships (MALAYA FORCE) into the Bay of Bengal where he destroyed 23 merchantmen, 20 of them in one day, and also bombed the Indian towns of Cocanada and Vizagapatan which caused little damage but much panic. Simultaneously, Japanese submarines added to the toll by torpedoing 32,000 tons of Allied shipping off India's west coast.

Two of Somerville's carriers were new, but his battleships were too old to keep up with them. He therefore planned a pre-emptive night attack that gave some protection from the 300 aircraft of Nagumo's five carriers. From ULTRA intelligence Somerville expected the attack on 1 April. When that date passed he had to divert his main force to his secret base at Addu Atoll in the Maldive Islands, to refuel and replenish its water supplies, and he sent the small carrier Hermes, two cruisers, Dorsetshire and Cornwall, and the Australian destroyer Vampire, to Ceylon for repair and escort duties. On 4 April, while at Addu, Somerville heard that Nagumo had been sighted 565 km. (350 mi.) to the south-east of Ceylon and though he immediately dispatched his ships there he was too late to pre-empt the attack.

Ceylon's Colombo harbour, Nagumo's first target, had been mostly cleared of shipping, but his aircraft, when they raided it on 5 April, sank a destroyer and an armed merchant cruiser. They also destroyed 27 British aircraft for a loss of 9 of their own. Other Japanese aircraft then sank Dorsetshire and Cornwall after the two cruisers had left Colombo to rejoin Somerville. Realizing that his carrier aircraft, notably inferior to the Japanese, were unable to protect his battleships, Somerville sent the latter to the Kenyan port of Kilindini (Mombasa) in British East Africa and warned the Admiralty that he could only ‘create diversions and false scents, since I am now the poor fox’. However, Nagumo's air reconnaissance failed to find what remained of the British fleet, though on 9 April his bombers raided another Sinhalese port, Trincomalee. These caused widespread damage, and more aircraft and shipping losses, including both Vampire and Hermes. But luckily for the British the Japanese had not planned to stay, and after this raid both Nagumo, who had lost just seventeen aircraft, and Ozawa withdrew.