The British Empire in the early decades of the 20th century, held sway over a population of 400–500 million people (roughly a quarter of the world's population), and covered nearly 30 million square kilometres, (roughly two-fifths of the world's land area).
The British Empire came together over 300 years through a succession of phases of expansion by trade, settlement or conquest, interspersed with intervals of pacific commercial and diplomatic activity, or imperial contraction. Its territories were scattered across every continent and ocean, and it was described with some truth as "the empire on which the sun never sets." Arguably, its zenith was achieved in the 1890s and 1900s.
The Empire facilitated the spread of British technology, commerce, language, and government around much of the globe. Imperial hegemony contributed to Britain's extraordinary economic growth, and greatly strengthened its voice in world affairs. Even as Britain extended its imperial reach overseas, it continued to develop and broaden democratic institutions at the homeland.
From the perspective of the colonies, the record of the British Empire is mixed. The colonies received from Britain the English language, an administrative and legal framework on the British model, and technological and economic development. During decolonisation, Britain sought to pass parliamentary democracy and the rule of law to its colonies, with varying degrees of success. However, almost all former British colonies have since chosen to join the Commonwealth of Nations, the association which replaced the Empire.
Nonetheless, British colonial policy was always driven to a large extent by Britain's trading interests. While settler economies developed the infrastructure to support balanced development, tropical African territories found themselves developed only as raw-material suppliers. British policies based on comparative advantage left many developing economies dangerously reliant on a single cash crop. A reliance upon the manipulation of conflict between ethnic and racial identities, in order to keep subject populations from uniting against the occupying power — the classic "divide and rule" strategy — left a legacy of partition or inter-communal difficulties in areas as diverse as Ireland, India, Zimbabwe, Sudan, Uganda, Iraq, Guyana and Fiji. Colonel Frank Kitson, in his book Gangs and Countergangs (1960), described how British colonial authorities in Kenya successfully manipulated the Mau Mau uprising so that it became warfare between rival factions; ultimately only 22 Whites were killed, as opposed to 18,000–30,000 natives.
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