The military history of the United Kingdom covers the period from the birth of the united Kingdom of Great Britain in 1707, with the political union of England and Scotland, to the present day. From the 18th century and with the expansion of the British Empire the military became one of largest and most powerful in the world but experienced a sudden decline in the latter 20th century in the wake of two world wars, de-colinization and the rise of the superpowers.

18th Century

• War of the Spanish Succession (1702–1713) - England and Scotland/Great Britain, Germany, Portugal and Holland v France and Spain
  • Queen Anne's War (1702–1713)
• Jacobite Rebellions 1715-16; 1719; 1745-46) - Civil War
  • Clifton Moor Skirmish, near Penrith (1745) - last battle on English soil
  • Battle of Culloden (1746) - last battle in Great Britain
• War of the Quadruple Alliance (1718–1720) - Great Britain, France, Austria and Holland v Italy and Spain
• War of Jenkins' Ear (1739–1742) - Great Britain v Spain
• War of the Austrian Succession (1742–1748) - Great Britain, Austria and Holland v France and Germany
  • King George's War (1744–1748)
• Seven Years' War (1756–1763) - the first "world war"
  • French and Indian War (1754–1763) - Great Britain and Germany v Austria, France, Russia, Sweden, Spain and Portugal
  • Anglo-Cherokee War (1759–1763) - North America
• Pontiac's Rebellion (1763–1766) - North America
• First Anglo-Mysore War (1766–1769) - India
• American War of Independence (1775–1783) - North America, civil war
• First Anglo-Maratha War (1775–1782) - India
• Fourth Anglo-Dutch War (1780–1784)
• Second Anglo-Mysore War (1780–1784) - India
• Third Anglo-Mysore War (1789–1792) - India

19th Century

• French Revolutionary Wars (1793–1802) - Great Britain, Austria, Spain, Russia, Germany v France
  • War of the First Coalition (1793–1797)
  • War of the Second Coalition (1798–1801)
• Fourth Anglo-Mysore War (1798–1799) - India
• Irish Rebellion (1798)
• Napoleonic Wars (1803–1815) - United Kingdom, Prussia, Austria, Sweden, Spain and Russia v France
  • South American War (1806–1807)
  • Anglo-Turkish War (1807–1809)
  • Anglo-Russian War (1807–1812)
  • Gunboat War (1807–1814)
  • Peninsular War (1808–1814)
  • Hundred Days (1815)
• First Kandian War (1803–1804) - India
• Second Anglo-Maratha War (1803–1805) - India
• Vellore Mutiny (1806) - India
• Anglo-Dutch Java War (1810–1811)
• War of 1812 (1812–1815)
• Anglo-Nepalese War (1814–1816)
• Second Kandian War (1815) - Sri Lanka
• Third Anglo-Maratha War (1817–1818) - India
• First Anglo-Burmese War (1823–1826)
• Upper Canada Rebellion (1837)
• Lower Canada Rebellion (1837)
• First Anglo-Afghan War (1839–1842)
  • Battle of Ghazni
• First Opium War (1839–1842) - United Kingdom v China
• First Anglo-Sikh War (1845–1846) - India
• New Zealand Wars (1845–1872)
• Second Anglo-Sikh War (1848–1849) - India
• Second Anglo-Burmese War (1852)
• Crimean War (1854–1856) - United Kingdom, France, Turkey, and Piedmont-Sardinia v Russia
• Second Opium War (1856–1860) - United Kingdom and France v China
• Anglo-Persian War (1856–1857) - United Kingdom and Persia
• Indian Rebellion (1857)
• Pig War (1859) - United Kingdom v USA
• Anglo-Bhutanese War (1865)
• Second Anglo-Afghan War (1878-1880)
• Anglo-Zulu War (1879)
• First Boer War (1880–1881)
• Gun War (1880–1881)
• Mahdist War (1881–1899)
• Third Anglo-Burmese War (1885–1887)
• Anglo-Zanzibar War (1896)
• Second Boer War (1899–1902)

20th Century

• Boxer Rebellion (1900) - United Kingdom, Austria-Hungary, France, Germany, Italy, Japan, Russia, USA, and China
• Anglo-Aro war (1901-1902) - Nigeria
• World War I (1914–1918) - United Kingdom, France, Belgium, Serbia, Italy, Russia, United States, Germany, Austria-Hungary, Bulgaria and Turkey
• Easter Rising (1916) - Ireland
• Russian Civil War (1918–1922)
• Third Anglo-Afghan War (1919)
• Anglo-Irish War (1919–1921)
• World War II (1939–1945) see Military history of the United Kingdom during World War II
  • The Pacific War (1937–1945)
  • Anglo-Iraqi War (1941)
• Greek Civil War (1941–1949)
• Malayan Emergency (1948–1960)
• Korean War (1950–1953)
• Mau Mau Uprising (1952–1960)
• Cyprus Emergency (1955–1959)
• Suez Crisis (1956)
• Brunei Revolt (1962)
• Indonesia-Malaysia confrontation (1962–1966)
• Aden Emergency (1963–1967)
• Northern Ireland Troubles (1969-mid 1990s)
• Cod War Confrontation (1975–1976)
• Falklands War (1982)
• The First Gulf War (1990–1991)
• The Bosnian War (1995–1996)
• The Kosovo War (1999)
• Sierra Leone Civil War (2000)

21st century

• The Global War on Terror (2001)
• The Afghanistan War (2001–Present)
• Iraq War and Iraqi insurgency (2003–Present)