British dominion over India was established through the East India Company after the Battle of Plassey in 1757 and passed to direct Crown rule after 1858. By the early twentieth century the system was under pressure from every side: economic extraction, recurring famines, the conscription of Indian soldiers into two world wars, and the rise of a national consciousness among an Indian middle class. Mohandas Gandhi turned the Indian National Congress into a mass movement through campaigns of nonviolent resistance — the 1930 Salt March and the 1942 'Quit India' movement above all. Over the same decades the Muslim League under Muhammad Ali Jinnah developed the 'two-nation' thesis, arguing that India's Muslims required a state of their own.

The Second World War left Britain financially exhausted; after 1945 London could no longer hold the empire. In March 1947 Lord Mountbatten was sent as the last Viceroy, and the date of withdrawal was brought forward to August 1947. To implement partition, the British lawyer Cyril Radcliffe — who had never set foot in India — was given just five weeks to draw a border through Punjab and Bengal, working from demographic maps. The resulting 'Radcliffe Line' was announced on 17 August, two days after independence itself. Pakistan was proclaimed at midnight on 14 August in Karachi; India in the first minutes of 15 August in Delhi, with Jawaharlal Nehru's 'tryst with destiny' speech marking the formal end of two centuries.

The Partition that followed displaced between 12 and 15 million people across the new borders — Hindus and Sikhs moving toward India, Muslims toward Pakistan. Refugee trains were massacred in Punjab and Bengal, villages burned; estimates range from one to two million dead, with more than 75,000 women subjected to sexual violence. Most historians describe the events as ethnic cleansing; responsibility is shared between Britain's hurried withdrawal, the failure of Congress and Muslim League leaders to compromise, and local political actors who organised the violence. In January 1948 Gandhi himself was assassinated by a Hindu nationalist for supporting payments to Pakistan. The first war over Kashmir broke out within weeks of independence, and the enmity between the two states has carried into the present.

August 1947 marks the beginning of the modern wave of decolonisation. Britain's release of 'the jewel of the Empire' was followed by Burma (1948), Ceylon (1948), the recognition of Indonesia (1949), and within twenty years the independence of most of Africa. Independence also set the basic outlines of contemporary South Asia: the world's largest democracy, two nuclear-armed rival states, and a region that would grow to three with the secession of Bangladesh in 1971. Partition remains one of the clearest examples of how much human suffering can be folded into the abstract idea of 'an empire unwinding'.