The Indo-Pakistani War of 1971 was a military conflict between India and Pakistan. The war is closely associated with the Bangladesh Liberation War (sometimes also referred to as the Pakistani Civil War). The armed conflict on India's western front during the period between 3 December 1971 and 16 December 1971 is called the "Indo-Pakistani War" by both the Bangladeshi and Indian armies, while Pakistan considers it a larger part of the East Pakistan rebellion. After 14 days of armed hostilities on two fronts, the war ended with the surrender of the Eastern Command of the Pakistan Military and secession of then East Pakistan, resulting in creation of the independent state of Bangladesh. Around 90,000 West Pakistanis who were in East Pakistan at the time of its independence, including some 54,000 Pakistan Army personnel and 12,000 civilians, were taken as prisoners of war (POWs) by India.
East Pakistan and West Pakistan had their own differences. The elections in Pakistan led to the dominance of a party primarily based in the East and the struggle for power within Pakistan resulted in the Pakistan president calling upon military forces to settle the dispute. The Pakistan army conducted a widespread genocide against the population of East Pakistan in particular to the minority Hindu population, leading to approximately 10 million people fleeing East Pakistan and taking refuge in the neighboring Indian state of West Bengal. On 27 March 1971, the Indian Prime Minister Indira Gandhi, expressed full support of her government to the struggle for independence by the people of East Pakistan. The East Pakistan-India border was opened to allow refugees safe shelter in India. The governments of West Bengal, Bihar, Assam, Meghalaya and Tripura established refugee camps along the border. The Indian leadership under Indira Gandhi quickly decided that it was more effective to end the genocide to take armed action against Pakistan than to simply give refuge to those who made it across to refugee camps.
Unable to deter India's activities in the eastern sector, on December 3, 1971, Pakistan launched an air attack in the western sector on a number of Indian airfields, including Ambala in Haryana, Amritsar , and Udhampur in Jammu and Kashmir. The attacks did not succeed in inflicting substantial damage. The Indian air force retaliated the next day and quickly achieved air superiority. On the ground, the strategy in the eastern sector marked a significant departure from previous Indian battle plans and tactics, which had emphasized set-piece battles and slow advances. The strategy adopted was a swift, three-pronged assault of nine infantry divisions with attached armored units and close air support that rapidly converged on Dhaka, the capital of East Pakistan. Lieutenant General Sagat Singh, who commanded the eighth, twenty-third, and fifty-seventh divisions, led the Indian thrust into East Pakistan. As these forces attacked Pakistani formations, the Indian air force rapidly destroyed the small air contingent in East Pakistan and put the Dhaka airfield out of commission. In the meantime, the Indian navy effectively blockaded East Pakistan. Dhaka fell to combined Indian and Mukti Bahini forces on December 16, bringing a quick end to the war. Action in the western sector was divided into four segments, from the cease-fire line in Jammu and Kashmir to the marshes of the Rann of Kutch in northwestern Gujarat. On the evening of December 3, the Pakistani army launched ground operations in Kashmir and Punjab. It also started an armored operation in Rajasthan. In Kashmir, the operations were concentrated on two key points, Punch and Chhamb. The Chhamb area witnessed a particularly intense battle where the Pakistanis forced the Indians to withdraw from their positions. In other parts of Kashmir, the Indians made some small gains along the cease-fire line. Indian forces responded with a massive coordinated air, sea, and land assault. Indian Air Force started flying sorties against Pakistan from midnight and quickly achieved air superiority.The main Indian Objective on the Western front was to prevent Pakistan from entering Indian soil. There was no Indian intention of conducting any major offensive into West Pakistan. Though the Indian conduct of the land war on the western front was somewhat timid, the role of the Indian air force was both extensive and daring. During the fourteen-day war, the air force's Western Command conducted some 4,000 sorties. There was little retaliation by Pakistan's air force, partly because of the paucity of non-Bengali technical personnel. Additionally, this lack of retaliation reflected the deliberate decision of the Pakistan Air Force headquarters to conserve its forces because of heavy losses incurred in the early days of the war.
The Instrument of Surrender of Pakistani forces stationed in East Pakistan was signed at Ramna Race Course in Dhaka at 16.31 IST on December 16, 1971, by Lieutenant General Jagjit Singh Aurora, General Officer Commanding-in-chief of Eastern Command of the Indian Army and Lieutenant General A. A. K. Niazi, Commander of Pakistani forces in Bangladesh. The war ended with the surrender of the Pakistani military to the allied forces of India and Bangladesh, jointly known as the Mitro Bahini. Bangladesh became an independent nation, the world's third most populous Muslim state. The loss of East Pakistan demoralized the Pakistani military.In 1972 the Simla Agreement was signed between India and Pakistan, the treaty ensured that Pakistan recognized the independence of Bangladesh in exchange for the return of the Pakistani PoWs. India treated all the PoWs in strict accordance with the Geneva Convention, rule 1925. It released more than 90,000 Pakistani PoWs in five months. Further, as a gesture of goodwill, nearly 200 soldiers who were sought for war crimes by Bengalis were also pardoned by India.The accord also gave back more than 13,000 km² of land that Indian troops had seized in West Pakistan during the war, though India retained a few strategic areas; most notably Kargil (which would in turn again be the focal point for a war between the two nations in 1999). This was done as a measure of promoting "lasting peace" and was acknowledged by many observers as a sign of maturity by India.