India celebrates Independence Day on August 15. Pakistan does so a day earlier, on August 14.It is an odd difference, considering that the two countries were created out of the same British Indian empire, under the same Indian Independence Act, which specified August 15, 1947 as the date on which the two new Dominions would be established.So how did the two countries end up with different Independence Days? And why was August 15 chosen in the first place?When Lord Louis Mountbatten arrived in India as the last Viceroy in March 1947, Britain had given him until June 1948 to transfer power. But Mountbatten soon concluded that the process could not wait that long.The political situation was deteriorating rapidly. The Congress and Muslim League could hardly get along for the interim government to work, the demand for Pakistan had hardened, and communal violence was threatening large parts of the country. Mountbatten therefore brought forward the transfer of power to August 1947.In Mountbatten and the Partition of India, Volume 2, by Lapierre Dominique and Collins Larry, the last Viceroy explains his reasons for doing so, “…We couldn’t have gone more slowly, for reasons which I’ll put to you now. The Interim Government, which I inherited and didn’t create… couldn’t operate… I had an absolute — not so much intuition, it was fairly obvious that it couldn’t last much longer — but belief that if I could announce an early date, I could hope to hold on to that. If I’d said, vaguely, “We won’t do it until June 1948” — which I could have done, the thing would have disintegrated. There wouldn’t have been any hope.”This rare 1947 photograph provided by the Ministry of Defence shows Lord Mountbatten, Edwina Mountbatten and Jawaharlal Nehru at the first Independence Day celebrations in New Delhi. And why did he zero in on August 15? In the same passage, Mountbatten explains, “When I named August 15, I admit I chose the anniversary of the surrender of the Japanese in Singapore but I had to name a date, and it was a good date.”Story continues below this adBefore his Viceroy role, Mountbatten had been the Supreme Allied Commander, South East Asia Command (SEAC) during World War II, from October 1943 until June 1946. He had directed Allied operations against the Japanese forces in Burma, India, and the surrounding theatre. Therefore, when the British empire decided to pack up and leave, it chose a date of significance to Britain, which marked its triumph in World War II, and did not calculate what the hasty transfer of power and Partition would do to the two new dominions.Also Read | Why Mountbatten hastened India’s independence by 10 months, and at what costThings moved extraordinarily quickly. The Indian Independence Bill was introduced in the British House of Commons on July 4, 1947. In a fortnight, legislation had been passed to create the two new Dominions of India and Pakistan, with August 15, 1947 specified as the date.Later, as the Governor-General of India, Mountbatten spoke in the Constituent Assembly on August 15, 1947. In the speech, he defended the super-fast timeline he had followed.“It is barely six months ago that Mr. Attlee invited me to accept the appointment of last Viceroy. He made it clear that this would be no easy task-since His Majesty’s Government in the United Kingdom had decided to transfer power to Indian hands by June 1948. At that time it seemed to many that His Majesty’s Government had set a date far too early. How could this tremendous operation be completed in 15 months. However, I had not been more than a week in India before I realised that this date of June 1948 for the transfer of power was too late rather than too early communal tension and rioting had assumed proportions of which I had no conception when I left England. It seemed to me that a decision had to be taken at the earliest possible moment unless there was to be risk of a general conflagration throughout the whole sub-Continent,” he said.Story continues below this adPrime Minister Shri Jawaharlal Nehru’s and Their Excellencies the Earl and Countess Mountbatten enjoying tea in Simla, during a holiday in 1948 (Wikimedia Commons)Many historians have since argued that had the British not been in such a tearing hurry, better arrangements could have been made to manage the fallout of the Partition, and the massive bloodshed could have been lessened, if not averted.Also Read | Why these 2 MP temples celebrated Independence Day on August 11 instead of August 15However, Mountbatten defended his decision throughout. In the same Constituent Assembly speech, he said, “My reason for hastening these processes was that, once the principle of division had been accepted, it was in the interest of all parties that it should be carried cut with the utmost speed.”The transfer of power to Pakistan took place in Karachi on August 14. Mountbatten was present for the ceremony because he was still the Viceroy of India. But on August 15, he was due to become the Governor General of independent India. He couldn’t have been present in Karachi on August 15 and then travel to New Delhi to perform the same function there on the same day.Thus, from 1948, Pakistan has celebrated August 14 as its Independence Day.Story continues below this adSome accounts also cite a religious reason for choosing the date. August 14, 1947 coincided with the 27th of Ramadan, a holy day for Muslims.