The British Army assigned alphanumeric codes to each operational theatre of war it fought in during World War One. These codes are most commonly found on Medal Index Cards and Rolls and usually corresponds to the theatre of war a soldier first served in. These alphanumeric differ slightly depending on when an individual first entered an operational theatre of war. Records of soldiers who saw active service only after 1 January 1916 will contain codes from the column on the right, whereas those who saw active service before that date, generally those individuals who won the 1914 or 1914-15 Star, will feature codes from the column on the left.
| Operational Service up to 31 December 1915 | Operational Service from 1 January 1916 |
|---|---|
| 1. Western European Theatre | 1. Western European Theatre a. France and Flanders b. Italy |
| 2. Balkan Theatre a. Greek Macedonia, Serbia and Bulgaria b. Gallipoli (Dardanelles) and Aegean Islands | 2. Balkan Theatre a. Greek Macedonia, Serbia, Bulgaria and European Turkey b. Gallipoli (Dardanelles) |
| 3. Egyptian Theatre | 3. Russia (4-5 August 1914 to 1-2 July 1920) |
| 4. African Theatre a. British East Africa, German East Africa, Rhodesia, Nyasaland and Uganda b. German South West Africa c. Cameroon d. Togoland e. Caprivi Zipfel Rhodesia | 4. Egyptian Theatre a. 4-5 November 1914 to 18-19 March 1916 b. 18-19 March 1916 to 1 November 1918 |
| 5. Asiatic Theatre a. Mesopotamia and Bushire b. South West Arabia c. Aden d. Muscat e. Seistan f. Tochi Valley g. Hafiz h. Katlang, Rastam and Swati i. Landekai Ridge j. Perim k. Kalat l. Katchin m. Tsing-Tau | 5. African Theatre a. East Africa, Nyasaland and Northern Rhodesia b. South West Africa c. Cameroon d. Nigeria e. Togoland |
| 6. Australasian Theatre a. German New Guinea b. Nauru c. German Samoa | 6. Asiatic Theatre a. Hejaz b. Mesopotamia c. Persia d. Trans-Caspia e. South West Arabia f. Aden g. Indian Frontier Regions h. Tsing-Tau |
| 7. Australasian Theatre a. New Britain b. New Ireland c. Kaiser Wilhelmland d. Admiralty Islands e. Nauru f. German Samoa |
