The British Empire was composed of the dominions, colonies, protectorates, mandates, and other territories ruled or administered by the United Kingdom and its predecessor states. It began with the overseas possessions and trading posts established by England between the late 16th and early 18th centuries. At its height it was the largest empire in history and, for over a century, was the foremost global power. By 1913 the British Empire held sway over 412 million people, 23% of the world population at the time, and by 1920 it covered 35,500,000 km2 (13,700,000 sq mi), 24% of the Earth's total land area. As a result, its constitutional, legal, linguistic, and cultural legacy is widespread. At the peak of its power, the phrase "the empire on which the sun never sets" was often used to describe the British Empire as the Sun was always shining on at least one of its territories.
All areas of the world that were ever part of the British Empire. Current British Overseas Territories have their names underlined in red.
During the Age of Discovery in the 15th and 16th centuries, Portugal and Spain pioneered European exploration of the globe, and in the process established large overseas empires. Envious of the great wealth these empires generated, England, France, and the Netherlands began to establish colonies and trade networks of their own in the Americas and Asia. A series of wars in the 17th and 18th centuries with the Netherlands and France left England and then, following the union between England and Scotland in 1707, Great Britain, the dominant colonial power in North America. Britain became the dominant power in the Indian subcontinent after the East India Company's conquest of Mughal Bengal at the Battle of Plassey in 1757.
The independence of the Thirteen Colonies in North America in 1783 after the American War of Independence resulted in Britain losing some of its oldest and most populous colonies. British attention soon turned towards Asia, Africa, and the Pacific. After the defeat of France in the Napoleonic Wars (1803–1815), Britain emerged as the principal naval and imperial power of the 19th century, and expanded its imperial holdings across the globe. The period of relative peace in Europe and the world (1815–1914) during which the British Empire became the global hegemon was later described as Pax Britannica ("British Peace"). In the early 19th century, the Industrial Revolution began to transform Britain; so that by the time of the Great Exhibition in 1851, the country was described as the "workshop of the world". Alongside the formal control that Britain exerted over its colonies, its dominance of much of world trade meant that it effectively controlled the economies of many regions, such as Asia and Latin America.
During the 19th century, Britain's population increased at a dramatic rate, accompanied by rapid urbanisation, which caused significant social and economic stresses. To seek new markets and sources of raw materials, the British government under Benjamin Disraeli initiated a period of imperial expansion in Egypt, South Africa and elsewhere. Canada, Australia, New Zealand, and South Africa became self-governing dominions.
By the start of the 20th century, Germany and the United States had begun to challenge Britain's economic lead. Military and economic tensions between Britain and Germany were major causes of the First World War, during which Britain relied heavily on its empire. The conflict placed enormous strain on the military, financial, and manpower resources of Britain. Although the British Empire achieved its largest territorial extent immediately after World War I, Britain was no longer the world's pre-eminent industrial or military power. In the Second World War, Britain's colonies in East and Southeast Asia were occupied by Japan. Despite the final victory of Britain and its allies, the damage to British prestige helped to accelerate the decline of the empire. India, Britain's most valuable and populous possession, achieved independence as part of a larger decolonisation movement in which Britain granted independence to most territories of the empire. The Suez Crisis confirmed Britain's decline as a global power, and the transfer of Hong Kong to China in 1997 marked for many the end of the British Empire. Fourteen overseas territories remain under British sovereignty. After independence, many former British colonies joined the Commonwealth of Nations, a free association of independent states. The United Kingdom is now one of 16 Commonwealth nations, a grouping known informally as the Commonwealth realms, that share a monarch, currently Queen Elizabeth II.