Indian Ocean Theatre

Prior to World War II, the Indian Ocean was an important maritime trade route between European nations and their colonial territories in East Africa, the Arabian Peninsula, British India, Indochina, the East Indies (Indonesia), and Australia for a long time. Naval presence was dominated by the Royal Navy Eastern Fleet and the Royal Australian Navy as World War II began, with a major portion of the Royal Netherlands Navy operating in the Dutch East Indies and the Red Sea Flotilla of the Italian ''Regia Marina'' operating from Massawa.

Axis naval forces gave a high priority to disrupting Allied trade in the Indian Ocean. Initial anti-shipping measures of unrestricted submarine warfare and covert raiding ships expanded to include airstrikes by aircraft carriers and raids by cruisers of the Imperial Japanese Navy. A ''Kriegsmarine'' ''Monsun Gruppe'' of U-boats operated from the eastern Indian Ocean after the Persian Corridor became an important military supply route to the Soviet Union.

Chronology

* 15 November 1939: Australian, British and French warships began patrolling the Indian Ocean when the German pocket battleship ''Admiral Graf Spee'' sank the tanker ''Africa Shell'' south of Madagascar.

1940

The ''Regia Marina'' Red Sea Flotilla based at Massawa provided a focal point for Indian Ocean naval activity following Italian declaration of war on 10 June 1940; although Indian Ocean patrols of ''Kriegsmarine'' merchant raiders required defensive dispersion of Allied cruisers after May.
* 23 March 1940: The Royal Navy established the Malaya Force of cruisers, destroyers and submarines to stop German merchant ships leaving the Dutch East Indies.
* 11 May 1940: German merchant raider ''Atlantis'' entered the Indian Ocean from the South Atlantic.Muggenthaler, p.115
* 7 June 1940: Italian warships began minelaying off Massawa and Assab.
* 10 June 1940: Eight Italian submarines began war patrols of the Indian Ocean from Massawa.Rohwer & Hummelchen, p.23 Some of these submarines were lost because leakage of chloromethane air conditioning refrigerants caused central nervous system poisoning of their crews from recirculating air during submerged operations.
* 10 June 1940: ''Atlantis'' captured the freighter ''Tirranna'' in the Central Indian Ocean.
* 16 June 1940: Italian submarine ''Galileo Galilei'' sank the tanker ''James Stove''.
* 19 June 1940: ''Galileo Galilei'' was captured by the British naval trawler ''Moonstone''.
* 23 June 1940: Italian submarine ''Torricelli'' sank before being sunk by accompanying destroyers.
* 24 June 1940: Italian submarine ''Galvani'' sank the sloop HMIS ''Pathan'' before being sunk by the sloop .
* 11 July 1940: ''Atlantis'' sank the freighter ''City of Bagdad'' south of India.
* 13 July 1940: ''Atlantis'' sank the freighter ''Kemmendine'' south of India.
* 2 August 1940: ''Atlantis'' sank the freighter ''Tallyrand'' in the central Indian Ocean.
* 17 August 1940: Royal Navy and Royal Australian Navy cruisers and destroyers covered the withdrawal of British troops from British Somaliland to Aden.
* 24 August 1940: ''Atlantis'' sank the freighter ''King City'' in the Central Indian Ocean.
* 26 August 1940: German merchant raider ''Pinguin'' sank the tanker ''Filefjell'' south of Madagascar.Muggenthaler, p.165
* 27 August 1940: ''Pinguin'' sank the tanker ''British Commander'' and the freighter ''Morviken'' south of Madagascar.
* 6 September 1940: Italian submarine ''Guglielmotti'' sank the tanker ''Atlas'' in the Red Sea.
* 9 September 1940: ''Atlantis'' sank the tanker ''Athelking'' in the central Indian Ocean.
* 10 September 1940: ''Atlantis'' sank the freighter ''Benarty'' in the central Indian Ocean.
* 12 September 1940: ''Pinguin'' sank the freighter ''Benavon'' east of Madagascar.
* 16 September 1940: ''Pinguin'' captured the freighter ''Nordvard'' in the central Indian Ocean.
* 20 September 1940: ''Atlantis'' sank the liner ''Commissaire Ramel'' west of Sumatra.
* 7 October 1940: ''Pinguin'' captured the tanker ''Storstad'' south of Java.
* 21 October 1940: was sunk during the battle of Mumbai to Suez Canal convoy BN 7.
* 22 October 1940: ''Atlantis'' captured the freighter ''Durmitor'' west of Sumatra.
* 9 November 1940: ''Atlantis'' sank the freighter ''Teddy'' west of Sumatra.
* 10 November 1940: ''Atlantis'' captured the tanker ''Ole Jacob'' west of Sumatra.
* 11 November 1940: ''Atlantis'' sank the freighter ''Automedon'' west of Sumatra.
* 18 November 1940: shelled Italian Somaliland.
* 18 November 1940: ''Pinguin'' sank the freighter ''Nowshera'' west of Australia.
* 20 November 1940: ''Pinguin'' sank the freighter ''Maioma'' west of Australia.
* 21 November 1940: ''Pinguin'' sank the freighter ''Port Brisbane'' west of Australia.
* 30 November 1940: ''Pinguin'' sank the freighter ''Port Wellington'' in the central Indian Ocean.

1941

Early focus was Allied neutralisation and capture of ''Regia Marina'' African naval bases, followed by invasions of Iraq in April and Iran in August, to displace governments friendly to the Axis powers. Later Allied focus was on destruction of ''Kriegsmarine'' commerce raiders and moving troops to defend against anticipated Japanese expansion into south-east Asia.
* 24 January 1941: German merchant raider ''Atlantis'' sank the freighter ''Mandasor'' north of Madagascar.
* 31 January 1941: ''Atlantis'' captured the freighter ''Speybank'' north of Madagascar.
* 2 February 1941: aircraft raided Mogadishu as Operation Breach. ''Atlantis'' captured the tanker ''Ketty Brövig'' north of Madagascar.
* 3 February 1941: German pocket battleship ''Admiral Scheer'' entered the Indian Ocean from the South Atlantic.
* 10 February 1941: , , , , and formed Force T supporting the Allied offensive against Italian Somaliland from Kenya.Rohwer & Hummelchen, p.51
* 13 February 1941: Fourteen Fairey Albacore from HMS ''Formidable'' sank SS ''Monacalieri'' in the Operation Composition raid on Massawa.
* 20 February 1941: ''Admiral Scheer'' sank the freighter ''Grigorios C'' and captured the tanker ''British Advocate'' north of Madagascar.
* 21 February 1941: Seven Fairey Albacore from HMS ''Formidable'' raided Massawa. ''Admiral Scheer'' sank the freighter ''Canadian Cruiser'' north of Madagascar.
* 22 February 1941: ''Admiral Scheer'' sank the freighter ''Rantaupandjang'' north of Madagascar.
* 27 February 1941: Action of 27 February 1941, sank the Italian merchant raider ''Ramb I'' west of the Maldives.
* 1 March 1941: Five Fairey Albacore from HMS ''Formidable'' raided Massawa.
* 3 March 1941: ''Admiral Scheer'' returned to the South Atlantic to evade Allied warships.
* 4 March 1941: The four surviving Italian submarines abandoned the Massawa base and escaped into the South Atlantic. The German supply ship ''Coburg'' and prize ''Ketty Brövig'' were scuttled when stopped by and HMNZS ''Leander'', north of Madagascar.
* 16 March 1941: Invasion of Berbera by Royal Navy Force D.Rohwer & Hummelchen, p.55
* 23 March 1941: The German SS ''Oder'' was scuttled when stopped by in the Gulf of Aden.
* 1 April 1941: The German SS ''Bertrand Rickmers'' was scuttled when stopped by HMS ''Kandahar''.
* 8 April 1941: Six Italian destroyers and 17 Axis merchant ships were sunk or scuttled when Allied troops captured Massawa. ''Atlantis'' left the Indian Ocean via the South Atlantic.
* 19 April 1941: British invasion of Basra prelude to the Anglo-Iraqi War.
* 25 April 1941: German merchant raider ''Pinguin'' sank the freighter ''Empire Light'' in the Arabian Sea.
* 28 April 1941: ''Pinguin'' sank the freighter ''Clan Buchanan'' in the Arabian Sea.
* 7 May 1941: ''Pinguin'' sank the tanker ''British Emperor'' in the Arabian Sea.
* 8 May 1941: sank ''Pinguin'' in the Arabian Sea.
* 10 June 1941: British invasion of Assab as Operation Chronometer.
* 26 June 1941: German merchant raider ''Kormoran'' sank the freighters ''Velebit'' and ''Mareeba'' in the Bay of Bengal.Muggenthaler, p.189
* 25 August 1941: The Royal Navy supported the Anglo-Soviet invasion of Iran.
* 7 September 1941: Axis aircraft sank the freighter ''Steel Seafarer'' in the Red Sea.
* 24 September 1941: ''Kormoran'' sank the freighter ''Stamatios G. Embiricos'' in the Arabian Sea.
* 19 November 1941: Battle west of Australia between and ''Kormoran'' destroyed both ships.
* 30 November 1941: Free French forces replaced Vichy French in the battle of La Réunion.
* 2 December 1941: Convoy BM 9A arrived in Singapore with troops from Colombo.
* 17 December 1941: Sparrow Force delivered 650 Dutch and Australian troops to Timor.
* 27 December 1941: Convoy WS 24 arrived in Mumbai with 20,000 troops loaded at Halifax Harbour.

1942

Japanese submarine cruisers began patrolling the Indian Ocean during the Dutch East Indies campaign. Following the attack on Pearl Harbor, the ''Kido Butai'' fast carrier task force raided Darwin, Australia to cover the invasion of Timor and raided Ceylon to cover transport of Japanese troops to Rangoon. ''Kriegsmarine'' merchant raiders were less able to avoid Allied patrols; but the battle of the Atlantic spilled over into the Indian Ocean around Cape Agulhas as German Type IX submarines began patrolling the east coast of Africa.
* 4 January 1942: sank the freighter ''Kwangtung'' south of Java.
* 8 January 1942: ''I-56'' sank the liners ''Van Rees'' and ''Van Riebeek'' south of Java.
* 11 January 1942: Japanese submarine ''I-66'' sank the freighter ''Liberty'' south of Java.
* 14 January 1942: sank the freighter ''Jalarajan'' west of Sumatra.
* 17 January 1942: sank the in the Sunda Strait.
* 19 January 1942: Japanese aircraft sank the liner ''Van Imhoff'' west of Sumatra.
* 20 January 1942: and Australian minesweepers sank the off Darwin.Rohwer & Hummelchen, p.116 sank the freighter ''Eidsvold'' off Christmas Island.
* 21 January 1942: ''I-66'' sank the freighter ''Nord'' off Rangoon.
* 22 January 1942: Japanese submarine ''I-64'' sank the liner ''Van Overstraten'' west of Sumatra.
* 27 January 1942: flew off 48 Hawker Hurricanes for the defence of Java.
* 30 January 1942: ''I-64'' sank the freighters ''Florence Luckenbach'', ''Jalapalaka'' and ''Jalatarang'' in the Bay of Bengal.
* 15 February 1942: ''I-65'' sank the freighter ''Johanne Justesen'' off Ceylon.
* 16 February 1942: An Allied troop convoy from Darwin to Timor was turned back by Japanese air attack.Rohwer & Hummelchen, p.123
* 19 February 1942: Japanese invasion of Bali. Bombing of Darwin by the ''Kido Butai'' sank , the tanker ''British Motorist'', the freighter ''Mauna Loa'', and liners ''Neptuna'' and ''Zealandia''.
* 20 February 1942: Japanese invasion of Timor. ''I-65'' sank the freighter ''Bhima'' in the Arabian Sea.
* 25 February 1942: sank the freighter ''Boero'' south of Java.
* 27 February 1942: Japanese aircraft sank off Tjilatjap.
* 28 February 1942: sank the freighter ''City of Manchester'' west of Sumatra, and ''I-4'' sank the freighter ''Ban Ho Guan'' south of Java.
* 1 March 1942: Japanese battleships ''Hiei'' and ''Kirishima'' sank USS ''Edsall'', and the freighter ''Tomohon'', and Japanese cruiser ''Ashigara'' sank south of Java.Brown, (1990) p.59 Japanese submarine ''I-2'' sank the freighter ''Parigi'', ''I-59'' sank the liner ''Rooseboom'' west of Sumatra, and sank the freighter ''Modjekerto'' south of Java.
* 2 March 1942: Japanese warships sank the freighter ''Prominent'' off Tjilatjap, and ''Hayashio'' captured the freighter ''Sigli''.
* 3 March 1942: Japanese warships sank south of Java, Japanese submarine ''I-1'' sank the freighter ''Siantar'' off Tjilatjap, and Japanese aircraft sank the liner ''Koolama'' in the Timor Sea.
* 4 March 1942: Japanese warships sank , and the tanker ''Francol'' south of Java. Japanese submarine ''I-62'' sank the freighter ''Merkus'' off Tjilatjap, and ''I-7'' sank the liner ''Le Maire''.
* 5 March 1942: ''Kido Butai'' aircraft sank the freighters ''Manipi'', ''Tohiti'', ''Rokan'', ''Kidoel'', ''Poelau Bras'' and ''Dayak'' raiding Tjilatjap. ''Poelau Bras'' lifeboats attacked.Rohwer & Hummelchen, p.127
* 7 March 1942: Allied naval forces covered the withdrawal of Allied troops from Rangoon.Rohwer & Hummelchen, p.128 Japanese battleships ''Kongo'' and ''Haruna'' sank the freighter ''Woolgar'' while shelling Christmas Island.
* 8 March 1942: Japanese troops captured Rangoon.
* 9 March 1942: Japanese troops captured Java.
* 11 March 1942: Japanese submarine ''I-2'' sank the freighter ''Chilka'' west of Sumatra.
* 12 March 1942: Japanese invasion of Medan
* 13 March 1942: Japanese submarine ''I-64'' sank the freighter ''Mabella'' in the Arabian Sea.
* 23 March 1942: Japan invaded and captured the Andaman and Nicobar Islands as Operation D.
* 25 March 1942: A troop convoy delivered the 56th Division (Imperial Japanese Army) to Rangoon as Operation U.
* 26 March 1942: ''Kido Butai'' sailed from the Netherlands East Indies for Operation C.
* 31 March 1942: Operation X Japanese invasion and battle of Christmas Island.
* 1 April 1942: torpedoed ''Naka'' off Christmas Island. sank ''Yae Maur'' and ''Shunsei Maru'' in the Strait of Malacca.
* 5 April 1942: Japanese carrier planes sank and in an Easter Sunday Raid.Rohwer & Hummelchen, p.132
* 6 April 1942: Japanese cruisers sank the liner ''Dardanus'' and freighters ''Silksworth'', ''Autolycus'', ''Malda'', ''Shinkuang'', ''Gandara'', ''Indora'', ''Bienville'', ''Selma City'', ''Ganges'', ''Banjoewangi'', ''Batavia'', ''Taksang'', ''Sinkiang'', ''Exmoor'' and ''Van der Capellen'' in the Bay of Bengal during Operation C. Japanese submarine ''I-5'' sank the freighter ''Washingtonian''.Cressman, p.86 Japanese aircraft sank off Sittwe.
* 7 April 1942: A troop convoy delivered the 18th Division (Imperial Japanese Army) to Rangoon as Operation U.
* 9 April 1942: Japanese carrier planes sank , , and auxiliaries ''Athelstane'' and ''British Sergeant'' off Trincomalee.
* 5 May 1942: British invasion of Diego Suarez.
* 8 May 1942: Ceylonese soldiers mutinied on the Cocos Islands.
* 10 May 1942: German commerce raider ''Thor'' captured the liner ''Nanking'' west of Australia.Muggenthaler, p.251
* 31 May 1942: Japanese midget submarines torpedoed and the tanker ''British Loyalty'' at Diego Suarez.Rohwer & Hummelchen, p.161
* 2 June 1942: ''Kofuku Maru'' was mined off Rangoon.
* 6 June 1942: sank the Liberty ship ''Melvin H. Baker''.
* 16 June 1942: ''Thor'' sank the tanker ''Olivia'' west of Australia.
* 19 June 1942: ''Thor'' captured the tanker ''Herborg'' west of Australia.
* 30 June 1942: ''I-10'' sank the freighter ''Express''.
* 4 July 1942: ''Thor'' captured the freighter ''Madrono'' west of Australia.
* 20 July 1942: ''Thor'' sank the freighter ''Indus'' west of Australia.
*1 August 1942: Operation Stab begins, a diversion attempt by the British Eastern Fleet.
* 10 September 1942: Madagascar surrendered to British forces.
* 22 September 1942: sank the freighter ''Paul Luckenbach''.
* 24 September 1942: sank the freighter ''Losmar''.
* 17 October 1942: sank the freighter ''Empire Chaucer'' south of South Africa.Blair, pp.72-81
* 23 October 1942: ''U-504'' sank the freighter ''City of Johannesburg'' east of South Africa.
* 26 October 1942: ''U-504'' destroyed the Liberty Ship ''Anne Hutchinson'' east of South Africa.
* 29 October 1942: sank the freighters ''Ross'' and ''Laplace'' south of South Africa.
* 31 October 1942: ''U-504'' sank the freighters ''Reynolds'' and ''Empire Guidon'' east of South Africa.
* 1 November 1942: sank the troopship ''Mendoza'' east of South Africa.
* 3 November 1942: ''U-504'' sank the freighter ''Porto Alegre'' south of South Africa.
* 4 November 1942: ''U-178'' sank the freighters ''Hai Hing'' and ''Trekieve'' east of South Africa.
* 7 November 1942: ''U-159'' sank the freighter ''La Salle'' south of South Africa.
* 8 November 1942: sank the freighter ''Plaudit'' south of South Africa.
* 9 November 1942: Italian submarine sank the Liberty Ship ''Marcus Whitman''.
* 10 November 1942: ''U-181'' sank the freighter ''K.G. Meldahl'' south of South Africa.
* 11 November 1942: Japanese merchant raider ''Hōkoku Maru'' was sunk by the tanker '' Ondina'' and its escort .
* 13 November 1942: ''U-178'' sank the freighter ''Louise Moller'', and ''U-181'' sank the freighter ''Excello'' east of South Africa.
* 19 November 1942: sank the freighter ''Scottish Chief'', and ''U-181'' sank the freighter ''Gunda'' east of South Africa.
* 20 November 1942: ''U-177'' sank the Liberty ship ''Pierce Butler'',Cressman, p.133 and ''U-181'' sank the freighter ''Corinthiakos'' east of South Africa.
* 21 November 1942: ''U-181'' sank the freighter ''Alcoa Pathfinder'' east of South Africa.
* 24 November 1942: ''U-181'' sank the freighters ''Mount Helmos'' and ''Dorington Court'' east of South Africa.
* 26 November 1942: German blockade runner ''Ramses'' scuttled when stopped by escorts of convoy OW 1.Rohwer & Hummelchen, p.179
* 27 November 1942: ''U-178'' sank the Liberty ship ''Jeremiah Wadsworth'' south of South Africa.
* 28 November 1942: ''U-177'' sank the troopship drowning 750, and ''U-181'' sank the freighter ''Evanthia'' east of South Africa.
* 30 November 1942: German commerce raider ''Michel'' sank the freighter ''Sawokla'',Muggenthaler, p.258 ''U-177'' sank the troopship ''Llandaff Castle'' east of South Africa, and ''U-181'' sank the freighter ''Cleanthis'' in the Mozambique Channel.
* 1 December 1942: was sunk by Japanese aircraft while evacuating personnel from Timor.
* 2 December 1942: ''U-181'' sank the freighter ''Amarylis'' east of South Africa.
* 7 December 1942: ''Michel'' sank the freighter ''Eugenie Livonos'' east of South Africa, and ''U-177'' sank the freighter ''Saronikos'' in the Mozambique Channel.
* 12 December 1942: ''U-177'' sank the freighter ''Empire Gull'' east of South Africa.
* 14 December 1942: ''U-177'' sank the freighter ''Sawahloento'' east of South Africa.

1943

Axis submarine patrols of Indian Ocean trade routes were expanded with establishment of a ''Kriegsmarine'' base in Penang as Allied anti-submarine patrols became increasingly effective in the Atlantic. Allied submarines and aircraft began patrolling the Strait of Malacca and Andaman Sea to intercept shipping supporting Japanese forces in Burma.
* 10 January 1943: evacuated 313 troops and civilians from Timor.Rohwer & Hummelchen, p.188
* 15 January 1943: Five-hundred Allied prisoners of war drowned when Tenth Air Force B-24 Liberators sank the ''Nichimei Maru'' in the Andaman Sea.
* 11 February 1943: sank the freighter ''Helmsprey'' east of South Africa.Blair, pp.226-233
* 17 February 1943: sank the freighter and ''U-516'' sank the freighter ''Deer Lodge'' east of South Africa.
* 18 February 1943: Convoy Prophet returned 30,000 soldiers of the Australian 9th Division from Africa to Australia.
* 26 February 1943: ''Kyo Maru'' No. 3 was mined off Rangoon.Cressman, p.147
* 27 February 1943: Tenth Air Force B-24s sank ''Asakasan Maru'' in the Andaman Sea. ''U-516'' sank the Dutch submarine tender ''Columbia'' east of South Africa.
* 3 March 1943: sank the Liberty ship ''Harvey W. Scott'' and the freighter ''Nipura'' east of South Africa.
* 4 March 1943: ''U-160'' sank the freighters ''Marietta'' and ''Empire Mahseer'' east of South Africa.
* 7 March 1943: sank the freighter ''Sabor'' east of South Africa.
* 8 March 1943: ''U-160'' sank the Liberty ship ''James B. Stephens'' east of South Africa.
* 9 March 1943: Interned German freighters ''Drachenfels'', ''Ehrenfels'' and ''Braunfels'' were scuttled at Goa. ''U-506'' sank the freighter ''Tabor'' south of South Africa.
* 11 March 1943: ''U-160'' sank the freighter ''Aelbryn'', and ''U-182'' sank the Liberty ship ''Richard D. Spaight'' east of South Africa.Cressman, p.152
* 13 March 1943: Dutch submarine O-21 sank ''Kasuga Maru'' No. 2.
* 20 March 1943: sank the freighter ''Fort Mumford'' off India.
* 5 April 1943: ''U-182'' sank the freighter ''Aloe'' east of South Africa.
* 18 April 1943: sank the tanker ''Corbis'' east of South Africa.
* 21 April 1943: Italian submarine sank the Liberty Ship ''John Drayton''.
* 11 May 1943: ''U-181'' sank the freighter ''Tinhow'', and sank the freighter '' Nailsea Meadow'' east of South Africa.Blair, pp.296-306
* 17 May 1943: sank the freighter ''Northmoor'' east of South Africa.
* 27 May 1943: ''U-181'' sank the freighter ''Sicilia'' in the Mozambique Channel.
* 29 May 1943: ''U-198'' sank the freighter ''Hopetarn'' east of South Africa.
* 1 June 1943: ''U-178'' sank the freighter ''Salabangka'' east of South Africa.
* 3 June 1943: ''I-27'' sank the freighter ''Montanan''.Cressman, p.162
* 5 June 1943: ''U-198'' sank the freighter ''Dumra'' east of South Africa.
* 6 June 1943: ''U-198'' sank the Liberty ship ''William King'' east of South Africa.
* 7 June 1943: ''U-181'' sank the freighter ''Harrier'' east of South Africa.
* 19 June 1943: sank the Liberty ship ''Henry Knox''.Cressman, p.165
* 27 June 1943: sank the Liberty Ship ''Sebastian Cermeno'' south of Madagascar.
* 2 July 1943: ''U-181'' sank the liner ''Hoihow'' east of Madagascar.
* 4 July 1943: ''U-178'' sank the freighters ''Breiviken'' and ''Michael Livanos'' in the Mozambique Channel.
* 5 July 1943: ''I-27'' damaged the freighter ''Alcoa Prospector''.
* 6 July 1943: ''U-177'' sank the freighter , and ''U-198'' sank the freighter ''Hydraios'' east of South Africa.
* 7 July 1943: ''U-198'' sank the freighter ''Leana'' in the Mozambique Channel.
* 9 July 1943: ''U-511'' sank the Liberty Ship ''Samuel Heintzelman'' in the central Indian Ocean.Cressman, p.168
* 10 July 1943: ''U-177'' sank the Liberty Ship ''Alice F. Palmer'' south of Madagascar.
* 11 July 1943: ''U-178'' sank the freighter ''Mary Livanos'' in the Mozambique Channel.
* 14 July 1943: ''U-178'' sank the Liberty ship ''Robert Bacon'' in the Mozambique Channel.
* 15 July 1943: ''U-181'' sank the freighter ''Empire Lake'' east of Madagascar.
* 16 July 1943: ''U-181'' sank the freighter ''Fort Franklin'' east of Madagascar.
* 17 July 1943: ''U-178'' sank the freighter ''City of Canton'' in the Mozambique Channel.
* 24 July 1943: sank the tanker ''Pegasus'' east of South Africa.
* 28 July 1943: Tenth Air Force B-24s sank ''Tamishima Maru'' in the Andaman Sea.
* 29 July 1943: ''U-178'' sank the freighter ''Cornish City'' east of South Africa.
* 1 August 1943: ''U-198'' sank the freighter ''Mangkalihat'' east of South Africa.
* 3 August 1943: ''U-196'' sank the freighter ''City of Oran'' in the Mozambique Channel.
* 4 August 1943: ''U-181'' sank the freighter ''Dalfram'' east of Madagascar.
* 5 August 1943: ''U-178'' sank the freighter ''Efthalia Mari'' east of Madagascar.
* 7 August 1943: ''U-181'' sank the freighter ''Umvuma'' east of Madagascar.
* 12 August 1943: ''U-181'' sank the freighter ''Clan Macarthur'' south of Madagascar.
* 17 August 1943: ''U-197'' sank the freighter ''Empire Stanley'' south of Madagascar.
* 20 August 1943: ''U-197'' was sunk east of South Africa by No. 259 Squadron RAF and No. 265 Squadron RAF Consolidated PBY Catalinas.
* 23 August 1943: Tenth Air Force B-24s sank ''Heito Maru'' in the Andaman Sea.
* 27 August 1943: German U-boat base established at Penang.Brice, pp.131-133
* 19 September 1943: sank the freighter ''Fort Longueuil'' east of Madagascar.Blair, pp.398-402
* 20 September 1943: Monsun Gruppe submarine surrendered at Durban after the Italian armistice.
* 21 September 1943: sank the Liberty ship ''Cornelia P. Spencer'' north of Madagascar.
* 24 September 1943: sank the Liberty ship ''Elias Howe''.
* 29 September 1943: ''U-532'' sank the freighter ''Banffshire'' in the Arabian Sea.
* 1 October 1943: ''U-532'' sank the freighter ''Tahsinia'' in the Arabian Sea.
* 2 October 1943: sank the freighter ''Haiching'' in the Arabian Sea.Blair, pp.398-402
* 11 October 1943: ''U-532'' sank the freighter ''Jalabala'' in the Arabian Sea.
* 16 October 1943: No. 244 Squadron RAF Bristol Blenheims sank in the Persian Gulf.
* 13 November 1943: sank in the Strait of Malacca.
* 3 December 1943: Allied aircraft sank the steamer ''Assam'' near Rangoon.Cressman, pp.197 & 198
* 5 December 1943: Japanese aircraft bombed Calcutta harbour.
* 7 December 1943: Operation Ratchet Allied at Regu Creek, Burma.
* 27 December 1943: ''U-178'' sank the Liberty ship ''José Navarro'' in the Arabian Sea.Cressman, p.200
* 28 December 1943: sank the Liberty ship ''Robert F. Hoke''.

1944

Use of Ultra intelligence information increased successful interceptions by Allied submarines and reduced Axis resupply opportunities in the Indian Ocean. Surrender of the ''Regia Marina'' and destruction of ''Kriegsmarine'' battleships made Royal Navy aircraft carriers available for raids of the Andaman Sea.
* 2 January 1944: sank the Liberty ship ''Albert Gallatin''.
* 11 January 1944: sank the Japanese cruiser ''Kuma'' in the Strait of Malacca.Rohwer & Hummelchen, p.255
* 15 January 1944: HMS ''Tally-Ho'' sank ''Ryuko Maru'' in the Strait of Malacca.
* 20 January 1944: ''U-188'' sank the freighter ''Fort Buckingham'' in the Arabian Sea.
* 23 January 1944: Tenth Air Force B-24 Liberators sank ''Seikai Maru'' in the Andaman Sea.
* 25 January 1944: ''U-188'' sank the freighter ''Fort la Maune'' in the Arabian Sea.
* 26 January 1944: ''U-532'' sank the Liberty ship ''Walter Camp'' in the Arabian Sea. ''U-188'' sank the liner ''Surada'' and the freighter ''Samouri'' in the Arabian Sea.
* 29 January 1944: ''U-188'' sank the freighter ''Olga E. Embiricos'' in the Arabian Sea.
* 3 February 1944: ''U-188'' sank the Liberty ship ''Chung Cheng'' in the Arabian Sea.
* 9 February 1944: ''U-188'' sank the freighter ''Viva'' in the Arabian Sea.
* 12 February 1944: The U-boat refuelling oiler ''Charlotte Schliemann'' scuttled when stopped by acting on Ultra.Blair, pp.527-542 sank the troopship drowning 1,279 passengers. then sank ''I-27''.
* 14 February 1944: HMS ''Tally-Ho'' sank the German submarine UIT-23 in the Strait of Malacca. sank the tug HMS ''Salviking'' south of India.
* 15 February 1944: sank the freighter ''Epaminondas C. Embiricos'' south of India.
* 18 February 1944: sank ''Eifuku Maru'' off Burma.
* 22 February 1944: sank the tankers ''San Alvaro'', ''Erling Brøvig'' and ''E.G. Seubert'' from convoy PA 69 in the Gulf of Aden.Blair, pp.465-468
* 29 February 1944: sank the freighter ''Palma'' south of Ceylon.
* 7 March 1944: sank the freighter ''Tarifa'' in the Arabian Sea.
* 9 March 1944: Japanese cruiser ''Tone'' sank the steamship ''Behar''. sank the tanker ''British Loyalty'' in the Maldives.
* 10 March 1944: and with sank Japanese submarine RO-110.Cressman, p.217
* 13 March 1944: The U-boat refuelling oiler ''Brake'' scuttled when found by aircraft from acting on Ultra. sank the tanker ''H.D. Collier''.
* 19 March 1944: sank the Liberty ship ''John A. Poor'' in the Arabian Sea.
* 27 March 1944: sank the naval trawler ''Maaløy'' in the Laccadive Sea. ''U-532'' sank the freighter ''Tulagi'' in the central Indian Ocean.
* 29 March 1944: sank the Liberty ship ''Richard Hovey''.
* 19 April 1944: Operation Cockpit air raid against northern Sumatra by and .
* 2 May 1944: was sunk off Somalia by No. 8 Squadron RAF and No. 621 Squadron RAF Vickers Wellingtons.
* 3 May 1944: sank ''Amagi Maru'' off Port Blair.
* 17 May 1944: Operation Transom air raid against Surabaya by HMS ''Illustrious'' and USS ''Saratoga''.
* 5 June 1944: sank the freighter ''Helen Moller'' in the central Indian Ocean.
* 19 June 1944: Operation Pedal air raid against Port Blair by HMS ''Illustrious'' and . ''U-181'' sank the freighter ''Garoet'' east of Madagascar.
* 9 July 1944: ''U-196'' sank the freighter ''Shahzada'' in the Arabian Sea.
* 15 July 1944: ''U-181'' sank the freighter ''Tanda'' in the Arabian Sea, and ''U-198'' sank the freighter ''Director'' in the Mozambique Channel.
* 17 July 1944: sank Japanese submarine ''I-166'' in the Strait of Malacca.Rohwer & Hummelchen, p.278
* 19 July 1944: ''U-181'' sank the freighter ''King Frederick'' in the Arabian Sea.
* 23 July 1944: sank ''Kiso Maru''.
* 25 July 1944: Operation Crimson air raid against northern Sumatra by HMS ''Illustrious'' and .
* 6 August 1944: ''U-198'' sank the freighter ''Empire City'' in the Mozambique Channel.
* 7 August 1944: ''U-198'' sank the freighter ''Empire Day'' in the Mozambique Channel.
* 12 August 1944: Allied aircraft and warships sank ''U-198'' north of Madagascar.
* 13 August 1944: sank the freighter ''Radbury'' in the Mozambique Channel.
* 16 August 1944: sank the freighter ''Empire Lancer'' in the Mozambique Channel.
* 18 August 1944: sank the freighter ''Nairung'' in the Mozambique Channel.
* 19 August 1944: sank the freighter ''Wayfarer'' in the Mozambique Channel.
* 20 August 1944: sank the freighter ''Berwickshire'' east of South Africa.
* 22 August 1944: shelled Christmas Island.
* 24 August 1944: Operation Banquet air raid against Padang by and ''Victorious''.
* 28 August 1944: sank the Liberty ship ''John Barry'' in the Arabian Sea.
* 1 September 1944: sank the freighter ''Troilus'' in the Arabian Sea.
* 5 September 1944: sank the freighter ''Toannis Fafalios'' north of Madagascar.
* 10 September 1944: Royal Air Force Beaufighters sank ''Misago Maru'' in the Andaman Sea.
* 23 September 1944: sank off Penang.
* 17 October 1944: Operation Millet raid against Port Blair by HMS ''Indomitable'' and ''Victorious''.
* 2 November 1944: shelled Port Blair.Rohwer & Hummelchen, p.316 ''U-181'' sank the tanker ''Fort Lee'' in the central Indian Ocean. Allied aircraft sank ''Tatayama Maru'' in the Andaman Sea.
* 18 November 1944: Operation Outflank air raid against northern Sumatra by HMS ''Indomitable'' and ''Illustrious''.
* 22 November 1944: was sunk by Japanese destroyers in the Strait of Malacca.
* 17 December 1944: Operation Robson air raid against northern Sumatra by HMS ''Indomitable'' and ''Illustrious''.
* 31 December 1944: sank ''Unryu Maru'' off Port Blair.

1945

Allied focus was on amphibious operations along the Burma coast of the Andaman Sea. Axis submarine operations were restricted by fuel shortage and maintenance difficulties.
* 3 January 1945: Operation Lightning Allied invasion of Akyab.
* 4 January 1945: Operation Lentil air raid against Sumatran oil refineries by , and .
* 12 January 1945: Allied amphibious landing near Myebon.
* 22 January 1945: Operation Matador Allied invasion of Kangaw.Rohwer & Hummelchen, p.329
* 24 January 1945: Operation Meridian air raid against Sumatran oil refineries by , ''Victorious'', ''Indomitable'' and ''Indefatigable''.
* 26 January 1945: Operation Sankey Allied invasion of Cheduba Island.
* 30 January 1945: Operation Crocodile Allied invasion of Sagu Island.
* 6 February 1945: sank the Liberty ship ''Peter Silvester'' west of Australia.
* 7 February 1945: sank ''Nanei Maru'' in the Andaman Sea.
* 11 February 1945: was knocked out of action by Japanese aircraft off Akyab.Rohwer & Hummelchen, p.334
* 16 February 1945: Allied invasion of Ruywa, Burma.
* 22 February 1945: Allied amphibious landing on the Myebon River.Rohwer & Hummelchen, p.335
* 24 February 1945: Operation Stacy air raid against Andaman Sea shipping by and .
* 8 March 1945: Tenth Air Force B-24 Liberators sank ''Hoyo Maru'' in the Andaman Sea.
* 17 March 1945: , and shelled Sigli.Rohwer & Hummelchen, p.340
* 19 March 1945: HMS ''Saumarez'', ''Rapid'' and ''Volage'' shelled Port Blair.
* 26 March 1945: The Royal Navy 26th Destroyer Flotilla sank ''Risui Maru'' and ''Teshio Maru'' in the Andaman Sea.
* 11 April 1945: Operation Sunfish air raid against Port Blair by and to cover shelling of northern Sumatra. No. 203 Squadron RAF B-24 Liberators sank ''Agata Maru'' in the Andaman Sea.
* 30 April 1945: Operation Dracula covering force destroyed a 9-ship Japanese convoy encountered en route.Rohwer & Hummelchen, p.350
* 1 May 1945: Operation Dracula amphibious landing near Rangoon.
* 6 May 1945: and ''Richelieu'' shelled Port Blair in Operation Bishop.
* 16 May 1945: The Royal Navy 26th Destroyer Flotilla sank the cruiser ''Haguro'' in the Battle of the Malacca Strait.
* 19 May 1945: was damaged by Japanese convoy escorts.Rohwer & Hummelchen, p.355
* 5 June 1945: The Royal Navy 10th Destroyer Flotilla sank the ''Kuroshio Maru'' evacuating troops from Port Blair.
* 20 June 1945: Operation Balsam air raid against northern Sumatra by , ''Ameer'' and ''Khedive''.
* 5 July 1945: Air raid against northern Sumatra by HMS ''Ameer'' and ''Emperor'' to cover Operation Collie minesweeping of the Andaman and Nicobar Islands.
* 26 July 1945: The first Indian Ocean kamikaze strike sank and damaged HMS ''Ameer'' during Operation Livery.Rohwer & Hummelchen, p.360

List of sub-theatres and actions

;Australia
* Axis naval activity in Australian waters
** Western Australian emergency of March 1944
* Air raids on Australia, 1942–43

;Britain
* Cocos Islands Mutiny

;France
* Battle of La Réunion
* Battle of Madagascar

;Germany
* Monsun Gruppe
* German auxiliary cruisers

;Japan
* Japanese occupation of the Andaman Islands
** Homfreyganj massacre
* Battle of Christmas Island
* Japanese raiders in the Indian Ocean Campaign
** Indian Ocean raid (1942)
*** Easter Sunday Raid
** Indian Ocean raid (1944)

Sources

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See also

* Pacific Theater aircraft carrier operations during World War II

Notes

{{Authority control

Naval battles and operations of World War II involving the United Kingdom
World War II operations and battles of the Southeast Asia Theatre