Japanese Attack Allied Harbor at Trincomalee

On 9 April 1942 the Japanese attacked the harbor at Trincomalee at 07:00.

The British again had warning of the attack, and Hermes and her escorts had left the night before. They were returning to port when they were discovered at 08:55. Hermes had no aircraft on board, and so was defenceless when 70 bombers attacked her at 10:35 off Batticaloa. Hit 40 times, Hermes sank with the loss of 307 men. Vampire and the corvette Hollyhock were also sunk.

The hospital ship Vita later picked up 590 survivors. The RAF lost at least eight Hawker Hurricanes and the Fleet Air Arm one Fairey Fulmar. The Japanese lost five bombers and six fighters, one in a suicide attack on the Trincomalee fuel tanks.

The sortie demonstrated Japanese superiority in carrier operations, and exposed the unprofessional manner in which the RAF was run in the East, but it did not destroy British naval power in the Indian Ocean. It is arguable that, by making full use of signal intercepts, decryption, reconnaissance and superior radar, Somerville was able to save his fast carriers Indomitable and Formidable to fight another day. However, it might equally be said that the blunders made by the Royal Navy meant that the main fleet from Addu was not able to make contact with Nagumo's force as it intended.
An invasion was feared by the British, who interpreted the Japanese failure to do so as due to heavy losses over Ceylon - and hence led to claims of a British victory. However, in reality the Japanese did not have the men, shipping or land based air power to spare for an invasion and occupation and were not even in a position to make a temporary occupation as a raid. The island did not face a real threat of invasion at any point during the war.

The island of Ceylon (Sri Lanka), was strategically important, since it commanded the Indian Ocean. Thus it controlled access to India, also the vital Allied shipping routes to the Middle East and the oilfields of the Persian Gulf. Ceylon held most of the British Empire's resources of rubber. An important harbor and naval base, Trincomalee, was located on the island’s eastern coast. Japanese propaganda had suborned many of the native Sinhalese population, who now awaited their arrival.

The raid had allowed the Imperial Japanese Navy to demonstrate their mastery of the Indian Ocean and Bay of Bengal; also their ability to seize territory by capturing the Andaman Islands. Despite losses, the British fleet escaped conflict by retiring; in view of the overwhelming superiority of the Japanese, particularly in carrier operations, this seems to have been a wise decision by Admiral Somerville. Japanese plans were already made for a submarine base in the island of Madagascar to attack Allied shipping routes; now a weakened Ceylon invited invasion, possibly with limited objectives, the taking of Trincomalee, a more convenient base.

That the British expected invasion, from their mastery of Japanese codes and other sources, is borne out by a speech, the C. in C. of Ceylon, Admiral Sir Geoffrey Layton, made in mid-April, to personnel of the damaged airfield, at China Bay in Trincomalee Harbor. He warned them, ‘The Japanese Fleet has retired to Singapore, to refuel and rearm, and to organise an invasion force, which we think is coming back to attack us.’ He ended by saying, ‘He was going for re-enforcements, while you men here, must be prepared to fight to the last man to stop the Japanese.' The Admiral’s speech had a negative effect on personnel, particularly his reference to leaving the island for re-enforcements; afterwards he became known as ‘Runaway Layton.’

However, the expected Japanese invasion never took place; the First Carrier Striking Force was recalled to Japan, due to events far away in the Pacific. The Doolittle Raid of April 18th 1942, was the first air raid by the United States on the Japanese home islands, during World War II. The totally unexpected raid on Tokyo, the capital and home of the Emperor, caused little damage, but had strong effects in the Japanese High Command. U.S. bombers had flown near the Imperial Palace, so insulting their revered Emperor; more important was their realization that the home islands were now vulnerable to U.S. air attack. The Imperial Japanese Navy had responsibility for securing the ‘Pacific Frontier’, thus would have to fix the problem.

Their Commander in Chief, Admiral Isoroku Yamamoto, now took charge of a complex operation, which would involve the taking of Midway Island, with the luring of U.S. Navy aircraft carriers into a fatal battle. Instead, in June 1942, the U.S. Navy would turn the tables and all four aircraft carriers of the First Striking Force would be sunk at the Battle of Midway, thus depriving the IJN of the ability to conduct long range strategic attacks.

Three British army divisions came to strengthen Ceylon’s defences; also measures to improve morale ensued, such as ensuring Sinhalese food rations were increased. Several minor mutinies against the British by native soldiers were quickly put down. Admiral Sir G. Layton remained in Ceylon for most of the war. Later, Ceylon would become an important base for the planned re-taking of Malaya and Singapore.[

Japanese bombers had failed to see the Hermes and her Australian destroyer escort Vampire at the Trincomnalee Naval base during their raid. Now finished with her repairs, Hermes was stripped of her aircraft to be used for the defense of Ceylon. She played a cat and mouse game with Japanese spotters by slipping out into the open water the night of 8 April before a planned return to base the next morning. At 7 am, Japanese bombers hit Trincomalee with a vengeance. One Japanese pilot made a suicide run on the Trincomalee fuel farm causing heavy damage. The RAF was able to throw only 22 fighters into the air plus eight bombers to seek out the Japanese carrier force without success