The military history of the United Kingdom covers the period from the creation of the united Kingdom of Great Britain, with the political union of England and Scotland in 1707, to the present day.
From the 18th century onwards, with the expansion of the British Empire and the country's industrial strength, the British military became one of the most powerful and technologically advanced militaries in Europe and the world. Its navy in particular, with major bases in four Imperial fortresses and coaling stations surrounding the globe, was the world's greatest naval force from the 18th to the mid-20th century. British military declined in the mid-20th century as did those of the traditional European continental powers following the two world wars, decolonisation, and the rise of the United States and the Soviet Union as the new superpowers. However, Britain remains a major military power with frequent military interventions around the world since the end of the Cold War in 1991. The present-day British Armed Forces encompass the Royal Navy, the British Army, and the Royal Air Force.
Britain has been involved in a great many armed conflicts since the union in 1707, on all continents except for Antarctica.