'Open Door' naval undertaking to rescue the Norwegian inhabitants of Sørøya, a large island at the mouth of the Altafjord in German-occupied northern Norway (15 February 194... Read More

'Operation 101' was a Japanese naval air offensive against Chunking and other areas of Szechuan province held by the Chinese Nationalist forces of Generalissimo Chiang Kai-she... Read More

'Operation 5' was the Japanese planned seizure of the Chinese province of Sichuan, which was also known as the 'Sichuan Invasion', 'Sichuan Invasion', 'Chungking Operation' an... Read More

'Operation 60,000' was the Romanian and German two-phase naval evacuation of the forces of Generaloberst Erwin Jaenecke’s 17th Army, of Generaloberst Ferdinand Schörner’s... Read More

'Operation 81' was a Japanese reinforcement convoy in the South-West Pacific theatre leading to the Battle of the Bismarck Sea (28 February/4 March 1943)., 'Operation 81' was ... Read More

'Operazione C.2' was the Italian occupation of the Vichy French island of Corsica within the context of 'Anton' (11 November 1942)., The Italian occupation of this island had ... Read More

'Operazione C.3' was the Italian alternative designation for the 'Esigenza C.3' and 'Herkules' combined operation to take Malta in July 1942 (4 May/27 June 1942). ... Read More

'Opernball' was a German air raid on London in south-eastern England (1/2 November 1940)., On this night 80 twin-engined bombers of Oberstleutnant Hans Korte’s Kampfgeschwad... Read More

'Ophelia' was a British undertaking to move forces from Palestine to Iraq (May 1941)., On 18 May Brigadier J. J. Kingstone’s 'Kingcol', the flying column of Major General J.... Read More

'Opium' (i) was the US transfer of the 3rd Marines from the continental USA to Samoa for onward transmission to the South Pacific combat area (September 1942)., The 3rd Marine... Read More

'Opium' (ii) was the British concentration of forces in the No. 1 Area of Admiral the Lord Louis Mountbatten’s South-East Asia Command and the movement of these forces to th... Read More

'Opossum' was an Australian raid by a party of the 'Z' Special Unit on the island of Ternate off Borneo to rescue the Sultan Iskander Muhammad Jabit Syah of Ternate., The miss... Read More

'Oppidan' (i) was the British second of a two-part reinforcement of Malta’s air defences with Supermarine Spitfire fighters delivered from the flight deck of the US fleet ca... Read More

'Oppidan' (ii) was an Allied undertaking to effect the transfer of large numbers of landing craft of all types from Europe to General Douglas MacArthur’s South-West Pacific ... Read More

'Opponent' (i) was a British multi-element naval and convoy operation to strengthen the defences of Malaya (January 1942)., Arriving in Singapore on 13 January, this was the s... Read More

This was a British naval operation in the South Atlantic including the ‘Portable’, ‘Rotary’ and ‘Spotter’ sub-operations (?). ... Read More

'Opponent' (iii) was a British unrealised naval undertaking for the destroyer Milne to transport Anthony Eden, the foreign secretary, from Plymouth to Lisbon for discussions w... Read More

'Optician' was an Allied naval undertaking for submarines to operate from Fremantle in Western Australia to land operatives of the Special Operations Executive at a number of ... Read More

'Orange' (ii) was the Free French occupation of Djibouti, the capital of French Somaliland on the northern side of the Horn of Africa, within 'Pentagon' (28 December 1942). ... Read More

'Orange' (iii) was the designation of German military convoys from Genichesk in the southern part of Ukraine across the Sea of Azov to Temryuk on the northern side of the Tama... Read More

'Orange Deal' was a Dutch attempt by Colonel de Ruyter van Steveninck’s Royal Netherlands Motorised Brigade (Prinses Irene Brigade) to secure a bridgehead on the right bank ... Read More

'Oration' (i) was a British offensive by Lieutenant General B. G. Horrocks’s X Corps of General Sir Bernard Montgomery’s 8th Army on the Axis positions at Enfidaville in s... Read More

'Oration' (ii) was an Allied mission to the partisan forces of Marshal Josip Broz Tito in German-occupied Yugoslavia (January 1944). ... Read More

'Orator' was a British air operation to deploy an element of the RAF’s No. 1 Photographic Reconnaissance Unit and No. 18 Group to the northern USSR to keep watch on the Germ... Read More

'Ordnance' was a British naval evacuation of Royal Marines, British army forces and Dutch personnel from the Hoek van Holland in the Netherlands as the German forces approache... Read More

The 'Orel Strategic Offensive Operation' was the Soviet offensive, more generally known as 'Kutuzov' and incorporating the 'Volkhov-Orel Offensive Operation' (12 July/18 Augus... Read More

The 'Orel-Bryansk Defensive Operation' was Soviet first of the seven sub-operations together constituting the 'Moscow Strategic Defensive Operation (30 September/23 October 19... Read More

The 'Orel-Kursk Defensive Operation' was the half of the Soviet 'Kursk Strategic Defensive Operation' to hold the 'Zitadelle' offensive of the Generaloberst Walter Model’s 9... Read More

'Orelob' was the Allied alternative designation ('Bolero' reversed) for 'Rhumba' (summer 1944). ... Read More

'Organdie' was a British special forces operation in the Shan States in the central eastern part of Japanese-occupied Burma (?). ... Read More

'Orient' was a German long-term and wholly tentative plan for the forces in North Africa and the Caucasus to advance and effect a junction in the Middle East (summer 1942)., T... Read More

'Orion' was a German naval and merchant navy operation in the Baltic Sea to transport refugees from Gotenhafen (Gdynia) in Poland to Copenhagen in German-occupied Denmark (30/... Read More

'Orkan' (i) was the German offensive to clear Crimea of its last Soviet defenders and pave the way for the 'Störfang' reduction of Sevastopol (24 September/16 November 1941).... Read More

'Orkan' (ii) was a German unrealised operation designed to eliminate the Sukhinichi salient on the Eastern Front (May/June 1942)., Confident in their belief that the Germans w... Read More

'Orkan' (iii) was a German counterattack on Lieutenant General Mark W. Clark’s US 5th Army 'Avalanche' beach-head at Salerno by Generalmajor Rudolf Sieckenius’s 16th Panze... Read More

'Orkan' (iv) was a U-boat wolfpack operation in the Norwegian Sea (5/10 March 1944)., The wolfpack comprised U-288, U-366, U-674 and U-990, and for the loss of Oberleutnant Br... Read More

'Orkan' (v) was a German undertaking against resistance forces in the Osuchy area of the Lublin region in German-occupied Poland (18 June 1942). ... Read More

'Orlog' was the German redeployment of the Junkers Ju 52/3m transport aircraft of Generaloberst Wolfram Freiherr von Richthofen’s Luftflotte IV for other tasks after their h... Read More

'Orm' was a British operation by the Special Operations Executive to establish a reception base centred on Trysil in the eastern part of German-occupied Norway (3 March/9 May ... Read More

'Orphan' (i) was a British programme of air attacks using radar-directed bombers for attacks on a number of sites associated with the German V-weapons programme (1944/8 May 19... Read More

'Orphan' (ii) was the British air courier service between the UK and Athens, the capital of Greece, during the visit there of Prime Minister Winston Churchill (December 1944).... Read More

'OS' was the designation of Allied convoys (together with a numerical suffix) plying the route from Liverpool, UK, to Freetown, Sierra Leone (July 1941/May 1945)., This 'Outbo... Read More

'Öse' was a German naval minelaying operation by two ex-Italian torpedo boats of Korvettenkapitän Wirich von Gartzen’s 10th Torpedoboots-Flottille to the north-west of the... Read More

'Oskar' was a German naval minelaying operation by the torpedo boats Iltis and Jaguar of Korvettenkapitän Hans Marks’s 6th Torpedoboots-Flottille in the Strait of Dover (2/... Read More

The 'Osovets Offensive Operation' was the Soviet final phase of the 'Belorussian Strategic Offensive Operation', otherwise known as 'Bagration' (6/14 August 1944)., Within 'Ba... Read More

'Osprey' was a British operation by the Special Operations Executive for a party to work in the Stavanger area of German-occupied Norway, establish radio contact, prepare loca... Read More

'OSS' was the British extension of the 'OS' convoy route to the south from Freetown, Sierra Leone, to Takoradi, Gold Coast (summer 1942/summer 1943). ... Read More

'Ossining' was a US series of special forces undertakings by the Office of Strategic Services' Maritime Unit, under the command of Lieutenant Richard Kelly of the US Navy, aga... Read More

'Ost' (i) was a German case study for the optimisation of the internal transportation system to facilitate the planned 'Weiss' (i) campaign against Poland (13 January/August 1... Read More

'Ost' (ii) was a German small-scale undertaking to seal the border between Poland and German-occupied Slovakia at the time of 'Weiss' (i) using Landesschützenbataillone terri... Read More