• 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. • 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. 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. • 24 August 1940:
Atlantis sank the freighter
King City in the Central Indian Ocean. • 27 August 1940:
Pinguin sank the tanker
British Commander and the freighter
Morviken south of Madagascar. • 9 September 1940:
Atlantis sank the tanker
Athelking in the central Indian Ocean. • 22 October 1940:
Atlantis captured the freighter
Durmitor west of Sumatra. • 18 November 1940:
Pinguin sank the freighter
Nowshera west of
Australia.
Atlantis captured the tanker
Ketty Brövig north of Madagascar. • 10 February 1941: , , , , and formed Force T supporting the Allied offensive against
Italian Somaliland from
Kenya. • 13 February 1941: Fourteen
Fairey Albacore from HMS
Formidable sank SS
Monacalieri in the
Operation Composition raid on Massawa. The German supply ship
Coburg and prize
Ketty Brövig were scuttled when stopped by and HMNZS
Leander, north of Madagascar. • 23 March 1941: The German SS
Oder was scuttled when stopped by in the
Gulf of Aden.
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. • 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. • 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. • 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. • 19 January 1942: Japanese aircraft sank the liner
Van Imhoff west of Sumatra. sank the freighter
Eidsvold off
Christmas Island.
Jalapalaka and
Jalatarang in the
Bay of Bengal. • 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. • 28 February 1942: sank the freighter
City of Manchester west of Sumatra, and
I-4 sank the freighter
Ban Ho Guan south of Java. 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. • 7 March 1942: Allied naval forces covered the withdrawal of Allied troops from Rangoon. Japanese battleships
Kongo and
Haruna sank the freighter
Woolgar while shelling Christmas Island. • 8 March 1942: Japanese troops captured Rangoon. • 13 March 1942: Japanese submarine
I-64 sank the freighter
Mabella in the Arabian Sea. • 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. • 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. Japanese aircraft sank off
Sittwe. • 7 April 1942: A troop convoy delivered the
18th Division (Imperial Japanese Army) to Rangoon as Operation U. • 8 May 1942: Ceylonese soldiers
mutinied on the
Cocos Islands. • 10 May 1942: German commerce raider
Thor captured the liner
Nanking west of Australia. • 31 May 1942: Japanese
midget submarines torpedoed and the tanker
British Loyalty at Diego Suarez. • 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. • 4 July 1942:
Thor captured the freighter
Madrono west of Australia. • 24 September 1942: sank the freighter
Losmar. • 17 October 1942: sank the freighter
Empire Chaucer south of South Africa. • 23 October 1942:
U-504 sank the freighter
SS City of Johannesburg east of South Africa. • 29 October 1942: sank the freighters
Ross and
Laplace south of South Africa. • 10 November 1942:
U-181 sank the freighter
K.G. Meldahl south of South Africa. • 13 November 1942:
U-178 sank the freighter
Louise Moller, • 19 November 1942: sank the freighter
Scottish Chief, and
U-181 sank the freighter
Gunda east of South Africa. and
U-181 sank the freighter
Corinthiakos east of South Africa. • 27 November 1942:
U-178 sank the Liberty ship
Jeremiah Wadsworth south of South Africa.
U-177 sank the troopship
Llandaff Castle east of South Africa, and
U-181 sank the freighter
Cleanthis in the
Mozambique Channel. • 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. • 17 February 1943: sank the freighter and
U-516 sank the freighter
Deer Lodge east of South Africa. • 26 February 1943:
Kyo Maru No. 3 was mined off
Rangoon. • 27 February 1943: Tenth Air Force B-24s sank
Asakasan Maru in the Andaman Sea. and the freighter
Nipura east of South Africa. • 9 March 1943: Interned German freighters
Drachenfels,
Ehrenfels and
Braunfels were scuttled at
Goa.
U-506 sank the Norwegian freighter
Tabor south of South Africa. • 13 March 1943:
Dutch submarine O-21 sank
Kasuga Maru No. 2. • 11 May 1943:
U-181 sank the freighter
Tinhow, and sank the freighter
Nailsea Meadow east of South Africa. • 17 May 1943: sank the freighter
Northmoor east of South Africa. • 5 June 1943:
U-198 sank the freighter
Dumra east of South Africa. • 27 June 1943: sank the Liberty Ship
Sebastian Cermeno south of
Madagascar. • 6 July 1943:
U-177 sank the freighter , and
U-198 sank the freighter
Hydraios east of South Africa. • 10 July 1943:
U-177 sank the Liberty Ship
Alice F. Palmer south of Madagascar. • 15 July 1943:
U-181 sank the freighter
Empire Lake east of Madagascar. • 29 July 1943:
U-178 sank the freighter
Cornish City east of South Africa. • 27 August 1943: German U-boat base established at Penang. • 14 September 1943: sank the tanker
Bramora south-west of Chagos Islands. • 19 September 1943: sank the freighter
Fort Longueuil east of Madagascar. • 20 September 1943:
Monsun Gruppe submarine surrendered at
Durban after the Italian armistice. • 24 September 1943: sank the Liberty ship
Elias Howe. • 29 September 1943:
U-532 sank the freighter
Banffshire in the
Arabian Sea. • 11 October 1943:
U-532 sank the freighter
Jalabala in the Arabian Sea. • 3 December 1943: Allied aircraft sank the steamer
Assam near Rangoon. • 5 December 1943: Japanese aircraft bombed
Calcutta harbour. • 28 December 1943: sank the Liberty ship
Robert F. Hoke. • 11 January 1944:
sank the Japanese cruiser
Kuma in the
Strait of Malacca. • 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. • 25 January 1944:
U-188 sank the freighter
Fort la Maune in the Arabian Sea.
U-188 sank the liner
Surada and the freighter
Samouri in the Arabian Sea. 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. • 22 February 1944: sank the tankers
San Alvaro,
Erling Brøvig and
E.G. Seubert from convoy PA 69 in the
Gulf of Aden. • 29 February 1944: sank the freighter
Palma south of
Ceylon. sank the tanker
British Loyalty in the
Maldives. • 13 March 1944: The U-boat refuelling oiler
Brake scuttled when found by aircraft from acting on Ultra. • 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. • 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.
U-181 sank the freighter
Garoet east of
Madagascar. • 19 July 1944:
U-181 sank the freighter
King Frederick in the Arabian Sea. • 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. • 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. • 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. • 23 September 1944: sank off
Penang. • 2 November 1944: shelled Port Blair.
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. • 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. • 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. • 7 February 1945: sank
Nanei Maru in the Andaman Sea. • 11 February 1945: was knocked out of action by Japanese aircraft off Akyab. • 16 February 1945: Allied invasion of Ruywa, Burma. • 24 February 1945:
Operation Stacy air raid against Andaman Sea shipping by and . • 17 March 1945: , and shelled
Sigli. • 19 March 1945: HMS
Saumarez,
Rapid and
Volage shelled
Port Blair. • 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. • 1 May 1945: Operation Dracula amphibious landing near
Rangoon. • 19 May 1945: was damaged by Japanese convoy escorts. • 5 June 1945: The Royal Navy 10th Destroyer Flotilla sank the
Kuroshio Maru evacuating troops from Port Blair. • 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. ==List of sub-theatres and actions==