In February 1947, the new British official set over the Indian subcontinent, Lord Mountbatten, faced with the failure of the federal proposal, supported partition of India into two states: the current India, with a Hindu majority, under the control of the Congress Party, and Pakistan, with a Muslim majority, under the control of the Muslim League. Pakistan was further divided by being cut into two parts 900 miles apart.
The border between India and Pakistan was determined by a British Government-commissioned report. Pakistan came into being with two non-contiguous enclaves, East Pakistan (today Bangladesh) and West Pakistan, separated geographically by India. India was formed out of the majority Hindu regions of the colony, and Pakistan from the majority Muslim areas. On July 18, 1947, the British Parliament passed the Indian Independence Act that finalized the partition arrangement. The Government of India Act 1935 was adapted to provide a legal framework for the two new dominions. Following partition, Pakistan was added as a new member of the United Nations. The union formed from the combination of the Hindu states assumed the name India which automatically granted it the seat of British India (a UN member since 1945) as a successor state.
Massive population exchanges occurred between the two newly-formed states in the months immediately following Partition. Once the lines were established, about 14.5 million people crossed the borders to what they hoped was the relative safety of religious majority. Based on 1951 Census of displaced persons, 7,226,000 Muslims went to Pakistan from India while 7,249,000 Hindus and Sikhs moved to India from Pakistan immediately after partition. About 11.2 million or 78% of the population transfer took place in the west, with Punjab accounting for most of it; 5.3 million Muslims moved from India to West Punjab in Pakistan, 3.4 million Hindus and Sikhs moved from Pakistan to East Punjab in India; elsewhere in the west 1.2 million moved in each direction to and from Sind. There were massive killings of Sikhs by radical Muslims and a similar killings of Muslims by Sikh guerillas, leading to a severe communal hatred in the area The newly formed governments were completely unequipped to deal with migrations of such staggering magnitude, and massive violence and slaughter occurred on both sides of the border. Estimates of the number of deaths range around roughly 500,000, with low estimates at 200,000 and high estimates at 1,000,000. The trauma incurred in the process has been profound. Consequently relations between the two states, between them and some of their people, and between some of their groups have not normalized even after more than half a century; on the contrary they have consistently worsened with each passing year Punjab was badly affected. The mostly Muslim western part of the province became Pakistan's Punjab Province; the mostly Sikh and Hindu eastern part became India's Punjab state. Many Hindus and Sikhs lived in the west, and many Muslims lived in the east. Lahore and Amritsar were at the center of the problem, the British were not sure where to place them - make them part of India or Pakistan. The British decided to give Lahore to Pakistan, whilst Amritsar became part of India. The province of Bengal was divided into the two separate entities of West Bengal belonging to India, and East Bengal belonging to Pakistan. East Bengal was renamed East Pakistan in 1955, and later became the independent nation of Bangladesh after the Bangladesh Liberation War of 1971. While Muslim majority districts of Murshidabad was given to India, Hindu majority district Khulna and the Buddhist majority Chittagong division was given to Pakistan by the award.
Princely state of Kashmir and Jammu had majority Muslim population in Kashmir valley and majority Hindu population in Jammu and sparse population elsewhere. Maharajah of Jammu and Kashmir gave accession to India on outbreak of violence. This Kashmir conflict lead to 1947 war between India and Pakistan in that region.
1947 India Pakistan War
When the British relinquished their claims to paramountcy, the 562 independent princely states were given the option to join either of the two nations. A few princely states readily joined Pakistan, but the rest--except Hyderabad (the largest of the princely states with 132,000 square kilometers and a population of more than 14 million), Jammu and Kashmir (with 3 million inhabitants), and Junagadh (with a population of 545,000)--merged with India... The Hindu maharajah of predominantly Muslim Jammu and Kashmir remained uncommitted until armed tribesmen and regular troops from Pakistan infiltrated his domain, inducing him to sign the Instrument of Accession to India on October 27, 1947. The maharajah of Jammu and Kashmir, unpopular among his subjects, was reluctant to decide on accession to either dominion. He first signed agreements with both Pakistan and India that would provide for the continued flow of people and goods to Kashmir--as it is usually called--from both dominions. Alarmed by reports of oppression of fellow Muslims in Kashmir, armed groups from the North-West Frontier Province entered the maharajah's territory. Fearing that his forces would be unable to withstand the assault, the Maharajah asked for Indian military assistance. India set a condition that Kashmir must accede to India for it to receive assistance. The government of Pakistan refused to recognize the accession and denounced it as a fraud even though the Indian government announced that it would require an expression of the people's will through a plebiscite after the invaders were driven back. Pakistan launched an active military and diplomatic campaign to undo the accession. Whereupon the Government of India recognized the accession of the erstwhile princely state to India, and was considered the new Indian state of Jammu and Kashmir, Indian troops were sent to the state to defend it against the Pakistani forces.
The Indian military was called upon to defend the borders of the state of Jammu and Kashmir when tribals--principally Pathans--attacked from the northwest reaches of Kashmir on October 22, 1947. India's 161st Infantry Brigade was deployed and thwarted the advance of the tribal forces. In early November 1947, the 161st counterattacked and successfully broke through the enemy defenses. Despite early successes, the Indian army suffered a setback in December because of logistical problems. The problems enabled the forces of Azad Kashmir (Free Kashmir, as the part of Kashmir under Pakistani control is called) to take the initiative and force the Indian troops to retreat from the border areas. In the spring of 1948, the Indian side mounted another offensive to retake some of the ground that it had lost. No doubt fearing that the war might move into Pakistan proper, regular units of the Pakistani army became more actively involved. As the conflict escalated, the Indian leadership was quick to recognize that the war could not be brought to a close unless Pakistani support for the Azad Kashmir forces could be stopped. Accordingly, on the advice of Governor General Earl Louis Mountbatten (Britain's last viceroy in India in 1947 and governor general of India, 1947-48), the Indian government sought United Nations (UN) mediation of the conflict on December 31, 1947. There was some opposition to this move within the cabinet by those who did not agree with referring the Kashmir dispute to the UN. The UN mediation process brought the war to a close on January 1, 1949. In all, 1,500 soldiers died on each side during the war. The UN Security Council eventually brought about a cease-fire between Pakistani and Indian troops, which took place on January 1, 1949, thus ending the first Indo- Pakistani War, and directed that a plebiscite be held. The cease- fire agreement formalized the military status quo, leaving about 30 percent of Kashmir under Pakistani control.