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Indian Ocean raid

Indian Ocean raid
Part of World War II, Pacific War
British heavy cruisers HMS Dorsetshire and Cornwall under Japanese air attack and heavily damaged on 5 April 1942

British heavy cruisers HMS Dorsetshire and Cornwall under Japanese air attack and heavily damaged on 5 April 1942.
Date 31 March – 10 April 1942
Location Indian Ocean and Ceylon
Result Decisive Japanese victory
 United Kingdom
 United States
Commanders and leaders
James Somerville Chūichi Nagumo[1]
2 fleet carriers
1 light carrier
5 battleships
7 cruisers
15 destroyers
7 submarines
100+ aircraft
30 smaller warships
50+ merchant ships
5 fleet carriers
1 light carrier
4 battleships
7 cruisers
19 destroyers
5 submarines
350 aircraft
Casualties and losses
1 carrier
2 cruisers
2 destroyers
1 Armed Merchant Cruiser (AMC)
1 corvette
1 sloop
23 merchant ships sunk
40+ aircraft destroyed
20+ aircraft destroyed

The Indian Ocean raid (known in Japan as Operation C)[2] was a naval sortie by the fast carrier strike force of the Imperial Japanese Navy from 31 March – 10 April 1942 against Allied shipping and bases in the Indian Ocean. It was an early engagement of the Pacific campaign of World War II. The Japanese under Chūichi Nagumo compelled part of the Allied (largely Royal Navy) forces to retreat to East Africa, but Admiral Sir James Somerville kept his fast carrier division, Force A, " Indian waters, to be ready to deal with any attempt by the enemy to command those waters with light forces only."[3]


  • Prelude 1
  • Raid 2
    • First moves 2.1
    • Attack on Colombo 2.2
    • Trincomalee and Batticaloa 2.3
  • Aftermath 3
  • See also 4
  • References 5
    • Notes 5.1
    • Books 5.2
  • External links 6


The island of Ceylon was strategically important, since it commanded the Indian Ocean. Thus it controlled access to India, 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 harbour and naval base, Trincomalee, was located on the island’s eastern coast. Japanese propaganda had an effect on some of the Sinhalese population, who now awaited their arrival.

The fall of Singapore on 15 February 1942 broke the United Kingdom's eastern defensive perimeter of the Bay of Bengal; and Japanese occupation of the Andaman Islands on 23 March 1942 gave Japan control of the Andaman Sea enabling ships to resupply Japanese troops in the Burma Campaign for control of India. Both German and British authorities anticipated Japanese capture of Ceylon to solidify control of the Bay of Bengal and disrupt British resupply for defence of India, Australia, and perhaps the Middle East. Ceylon was hastily garrisoned by Australian troops returning from North Africa; and HMS Indomitable was relieved of naval duties to serve as a high-speed aircraft ferry shuttling available planes to Ceylon.[4]


First moves

The Japanese strike force advancing to the Indian Ocean. Ships shown from left to right are: Akagi, Soryu, Hiryu, Hiei, Kirishima, Haruna, and Kongo. Taken from Zuikaku, March 30

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 Chūichi Nagumo, had six carriers: Akagi, Ryūjō, Hiryū, Sōryū, Shōkaku, and Zuikaku. This powerful force left Staring Bay, Celebes on 26 March 1942.

To meet the expected IJN foray into the Indian Ocean, Admiral Somerville had assembled a large fleet consisting of Force A with 2 modern aircraft carriers, 1 modernized battleship, HMS Warspite, along with a number of cruisers and destroyers, and Force B consisting of 4 older, unmodernized R class battleships, the light aircraft carrier HMS Hermes along with an escort of cruisers and destroyers. Somerville also deployed a small number of submarines.[5][6]

Signal decrypts provided the British commander of the Eastern Fleet, Vice Admiral Sir James Somerville with warning of the Japanese sortie, and Somerville sortied from Port T (Addu Atoll) in the Maldive Islands, to meet the attack expected on 1 or 2 April, but Nagumo had delayed the Japanese sortie by several days. When the expected attack on Ceylon failed to take place, Somerville sent the carrier HMS Hermes back to Trincomalee, Ceylon, for repairs in preparation for Operation Ironclad, escorted by the Australian destroyer HMAS Vampire.[7] The heavy cruiser HMS Cornwall was sent to Ceylon to meet a troop convoy along with Dorsetshire, which wished to continue a needed refit.[8] The first Japanese raids were against shipping in the Bay of Bengal by the carrier Ryūjō and six cruisers under the command of Admiral Jisaburo Ozawa beginning on 4 April 1942.[9] They sank 23 ships. Five more were sunk by submarines off India's west coast.

On the evening of 4 April, the Japanese fleet was detected 400 mi (350 nmi; 640 km) south of Ceylon by a Catalina flying boat 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 an A6M2 Zero fighter from Hiryū. Upon receipt of Birchall's warning Somerville again sortied from Adu Atoll, as soon as his ships were ready to sail, but his fleet was now too far west to intercept the Japanese raid prior to its first attack against Ceylon.[10]

Attack on Colombo

HMS Cornwall burning and sinking on 5 April 1942

On 5 April 1942, the Japanese struck with a force of 125 aircraft, made up of 36 Aichi D3A2 dive bombers and 53 Nakajima B5N2 torpedo bombers, with 36 Zero fighters as escort. The aircraft, under the command of Commander Mitsuo Fuchida of Akagi—who had led the attack on Pearl Harbor—made landfall near Galle. The planes flew up the coast for half an hour in full view from land, but the RAF was not informed at Ratmalana. RAF aircraft were on the ground as the Japanese flew overhead.

The Japanese attacked the naval base at Colombo, Ceylon, sinking the armed merchant cruiser HMS Hector (which was due to be released back to trade) and the old destroyer HMS Tenedos in the harbour. Eighteen Japanese planes were lost to heavy anti-aircraft fire. The Japanese only admitted to five losses, three of them over land — as only three destroyed planes were discovered on land. The RAF lost at least 27 aircraft. Japanese search planes located Cornwall and Dorsetshire — commanded by Captain Augustus Agar—200 mi (170 nmi; 320 km) southwest of Ceylon where they were proceeding at high speed to rejoin Somerville's command. A second attack wave sank the ships, killing 424 men.[11] In the late afternoon, just before sunset, at 16:55 and again at 18:00, on 5 April 1942, two Royal Navy Fairey Albacores operating from the British aircraft carriers made contact with the Japanese carriers. One Albacore was shot down and the other damaged before an accurate sighting report could be made, frustrating Admiral Somerville's plans for a retaliatory night strike by his ASV radar equipped Albacore strike bombers. Somerville continued to probe for the IJN carriers on the night of 5 April 1942 failing to find the IJN ships. The RN's only opportunity to launch a strike against enemy aircraft carriers faded away.[12]

On 6 April heavy cruisers Kumano and Suzuya with destroyer Shirakumo sank the British merchant ships Silksworth, Autolycus, Malda and Shinkuang and the American ship Exmoor.[13] Also on 6 April, the Indian sloop HMIS Indus was sunk by air attack off the coast of Burma, off Akyab.

Trincomalee and Batticaloa

Hermes sinking after Japanese air attack on 9 April 1942.

On 9 April, the Japanese attacked the harbour at Trincomalee at 07:00. The British again had warning of the attack, and the carrier 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. The destroyer HMAS Vampire and the corvette HMS 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.

During the day, nine of the Royal Air Force’s No. 11 Squadron Bristol Blenheim bombers made the first ever Allied air attack against Nagumo's Carrier Force.[14] Bombing from 11,000 ft (3300 m) they scored no hits while losing five of their number to the Striking Force's Combat Air Patrol A6M2 Zeroes, four over the IJN Carriers (two of which were claimed by Kaname Harada) and one due to an encounter with IJN aircraft returning from the Hermes raid, but in return shot down one Zero.[15][16]


The Japanese sortie demonstrated their superiority in carrier operations, and revealed that the RAF had not had time to fully prepare its Ceylon-based defences, but it did not destroy British naval power in the Indian Ocean. Through the use of signal intercepts, decryption, reconnaissance and superior radar, Somerville was able to save the bulk of his fleet, including the carriers HMS Indomitable and Formidable to fight another day. However, it might equally be said that the errors 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. It must also be stated that Japanese fleet under Admiral Nagumo never located Admiral Somerville's main fleet while Nagumo's carriers were subjected to their first ever bombing attack on 9 April 1942.[17]

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.

Japanese plans were already made for a submarine base on the island of Madagascar to attack Allied shipping routes. The Royal Navy forestalled any attempt by the Japanese to establish a base on Madagascar by seizing that island in May 1942 during Operation Ironclad.

That the British expected invasion—from their mastery of Japanese codes and other sources—is borne out by a speech that Admiral Sir

Three British army divisions came to strengthen Ceylon’s defences against Japan and against a possible internal anti-British uprising; also measures to improve morale were implemented, 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 operations in support of Burma and carrier raids against Indonesia.[18]

See also



  1. ^
  2. ^ Canadian Department of National Defense, accessed 18.00 on 6 February 2011.
  3. ^ Roskill, p.29
  4. ^
  5. ^ Somerville, Sir James. Report of Proceedings (ROP) Of Eastern Fleet – 1942
  6. ^ Roskill, p.23
  7. ^ Roskill, p.26
  8. ^ Roskill, p.26
  9. ^ Roskill, p.28
  10. ^ Roskill, p.26
  11. ^ Roskill, p.27
  12. ^ Somerville
  13. ^
  14. ^ Parshall, p.145.
  15. ^ Shores 1993, p.426-7.
  16. ^
  17. ^ Shores 1993
  18. ^ Roskill


  • Crusz, Noel, The Cocos Islands Mutiny, Fremantle: Fremantle Arts Centre Press, 2001.
  • Uses recently translated Japanese sources.
  • Tomlinson, Michael The Most Dangerous Moment: The Japanese Assault on Ceylon 1942, London: William Kimber & Co Ltd, 1976, ISBN 955-564-000-9.

External links

  • Order of battle
  • Raids into Indian Ocean
  • Royal Air Force History: Battle for Ceylon

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