On August 15, 1947, India won independence: a moment of birth that was also an abortion, since freedom came with the horrors of the partition, when East and West Pakistan were hacked off the stooped shoulders of India by the departing British.

Seventy years later, it is hard to look back without horror at the savagery of the country's vivisection, when rioting, rape and murder scarred the land, millions were uprooted from their homes, and billions of rupees worth of property were damaged and destroyed.

Within months, India and Pakistan were embroiled in a war over Kashmir, the consequences of which still affect us today.

There was an intangible partition, too. Friendships were destroyed, families ruined, geography hacked, history misread, tradition denied, minds and hearts torn apart.

The creation and perpetuation of Hindu-Muslim antagonism was the most significant accomplishment of British imperial policy: the colonial project of "divide et impera" (divide and rule) fomented religious antagonisms to facilitate continued imperial rule and reached its tragic culmination in 1947.

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The British liked drawing lines on maps of other countries; they had done it in the Middle East after World War I, and they did it again in India. Partition was the coda to the collapse of British authority in India in 1947.

The killing and mass displacement worsened as people sought frantically to be on the "right" side of the lines the British were to draw across their homeland. More than a million people died in the savagery that accompanied the freedom of India and Pakistan; some 17 million were displaced, and countless properties destroyed and looted. Lines meant lives.

In that last, mad, headlong rush to freedom and partition, the British emerge with little credit. Before World War II, they had no intention of devolving power so rapidly, or at all. The experience of the elected governments in the last years of the British Raj confirmed that the British had never been serious about their proclaimed project of promoting the responsible governance of India by Indians.

When the elected ministries of the Indian National Congress quit office in protest against the British declaring war against Germany on India's behalf without consulting them, the British thought little of appointing unelected Muslim Leaguers in their place and, in many cases, assuming direct control of functions that had supposedly been devolved to Indians. They openly helped the Muslim League take advantage of this unexpected opportunity to exercise influence and patronage that their electoral support had not earned them and to build up support while their principal opponents languished in jail.

This was all part of the policy of divide and rule, systematically promoting political divisions between Hindus and Muslims, defined as the monolithic communities they had never been before the British.

The British had been horrified, during the Revolt of 1857, to see Hindus and Muslims fighting side by side and under each other’s command against the foreign oppressor. They vowed this would not happen again. “Divide et impera was an old Roman maxim, and it shall be ours”, wrote Lord Elphinstone. A systematic policy of fomenting separate consciousness among the two communities was launched, with overt British sponsorship. When restricted franchise was grudgingly granted to Indians, the British created separate communal electorates, so that Muslim voters could vote for Muslim candidates for Muslim seats. The seeds of division were sown, to prevent a unified nationalist movement that could overthrow the British.

No one in any responsible position in Britain as late as 1940 had any serious intention whatsoever of relinquishing the Empire or surrendering the jewel in His Majesty's Crown to a rabble of nationalist Indians clad in homespun. But the devastation of World War II meant that only one-half of the phrase could survive: bled, bombed and battered for six years, Britain could divide, but it could no longer rule.

The British - terrorised by German bombing, demoralised by various defeats and large numbers of their soldiers taken prisoner, shaken by the desertion of Indian soldiers and the mutiny of Indian sailors, shivering in the record cold of the winter of 1945-46, crippled by power cuts and factory closures resulting from a post-war coal shortage - were exhausted and in no mood to focus on a distant Empire when their own needs at home were so pressing.

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They were also more or less broke: American loans had kept the economy afloat and needed to be repaid, and even India was owed a sizable debt. Overseas commitments were no longer sustainable or particularly popular. Exit was the only viable option: the question was what they would leave behind - one India, two or several fragments?

Britain's own tactics before and during the war ensured that by the time departure came, the Muslim League had been strengthened enough to sustain its demand for a separate homeland for Muslims, and the prospects of a united India surviving a British exit had essentially faded. Divide et impera had worked too well: a device meant to perpetuate British rule in India ensured a united India could not survive without the British. Two countries was what it would be.

The task of dividing the two nations was assigned to Sir Cyril Radcliffe, a lawyer who had never been to India before and knew nothing of its history, society or traditions. Radcliffe, perspiring profusely in the unfamiliar heat, drew up his maps in less than five weeks, dividing provinces, districts, villages, homes and hearts - and promptly scuttled to Britain, never to return to India. The British Empire simply crumbled in disorder. The British were heedless of the lives that would be lost in their headlong rush to the exits.

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The scars of the partition have lasted 70 years, even though India has emerged as a thriving pluralist democracy while Pakistan - splitting into two with the secession of the East as Bangladesh in 1971 - and Bangladesh have encountered difficulties in maintaining democracy. But India's flourishing democracy of seven decades is no tribute to British rule. It is a bit rich for the British to suppress, exploit, imprison, torture and maim people for 200 years and then celebrate the fact that they are a democracy at the end of it.

If Britain's greatest accomplishment was the creation of a single political unit called India, fulfilling the aspirations of visionary Indian emperors from Ashoka to Akbar, then its greatest failure must be the shambles of that original Brexit - cutting and running from the land they had claimed to rule for its betterment, leaving behind a million dead, 17 million displaced, billions of rupees of property destroyed, and the flames of communal hatred blazing hotly across the ravaged land. There is no greater indictment of the failures of British rule in India than the tragic manner of its ending.

Shashi Tharoor is an elected member of India's parliament and chairs its Foreign Affairs Committee. He is the prize-winning author of 16 books, including, most recently, Inglorious Empire: What the British Did To India.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.