- World War I (1914-1918): Britain was one of the main Allied powers fighting against the Central Powers.
- Russian Civil War (1918-1921): Britain intervened in support of the White Russian forces against the Bolsheviks.
- Irish War of Independence (1919-1921): Britain fought against Irish nationalists seeking independence.
- Chanak Crisis (1922): Britain threatened war with Turkey over the control of the Dardanelles.
- Shanghai Incident (1925): British forces were involved in clashes with Chinese nationalists in Shanghai.
- General Strike (1926): British troops were deployed to maintain order during a general strike.
- Abyssinia Crisis (1935-1936): Britain imposed economic sanctions on Italy after it invaded Ethiopia.
- Spanish Civil War (1936-1939): Britain provided military support to the Spanish Republican government against the Nationalists.
- World War II (1939-1945): Britain was one of the main Allied powers fighting against the Axis powers.
- Greek Civil War (1946-1949): Britain intervened in support of the Greek government against the communist guerrillas.
- Malayan Emergency (1948-1960): Britain fought against communist insurgents in Malaya.
- Suez Crisis (1956): Britain, France, and Israel invaded Egypt in response to its nationalization of the Suez Canal.
- Mau Mau Uprising (1952-1960): British forces were deployed to suppress a rebellion by the Kikuyu people in Kenya.
- Cyprus Emergency (1955-1959): Britain fought against Greek Cypriot nationalists seeking union with Greece.
- Aden Emergency (1963-1967): Britain fought against nationalist insurgents in Aden.
- Borneo Confrontation (1962-1966): Britain supported Malaysia against Indonesia in a conflict over Borneo.
- Falklands War (1982): Britain fought against Argentina after it invaded the Falkland Islands.
- Gulf War (1990-1991): Britain joined a coalition of forces led by the United States to expel Iraqi forces from Kuwait.
- Kosovo War (1999): Britain joined NATO forces in airstrikes against Serbia over its treatment of ethnic Albanians in Kosovo.
- War in Afghanistan (2001-2021): Britain joined the United States and its allies in the war against the Taliban and al-Qaeda in Afghanistan.
- Iraq War (2003-2011): Britain joined the United States and its allies in the invasion and occupation of Iraq.
- Libyan Civil War (2011): Britain joined NATO forces in airstrikes against Libyan government forces in support of the rebels.