The causes of the Indo-Pakistan war of 1971 were as follows: 

Differences due to languages – Urdu and Bengali : After Mr. Jinnah became the Governor general of Pakistan, he declared in 1948, ‘Urdu alone would be the state language and the lingua franca of the Pakistan state’. The Bengalis in East Pakistan (present Bangladesh) didn’t appreciate it. They launched an agitation that peaked in 1952. The Pakistan Government relented and granted it the official recognition in 1956. 

Political alienation : The East Pakistan was not treated and ruled well by the central Pakistan leadership. When military leaders began to rule the nation, they were even more one-sided with the West Pakistan and the alienation increased. Sheikh Mujibur Rehman, the leader of East Pakistan fought for the rights of East Pakistan. He came up with Six Points movement. It basically sought equal power for the East Pakistan on political, budgetary and military resources. The military leadership of West Pakistan didn’t heed it. Sheikh Mujibur Rehman and East Pakistan felt they were seeking more powers and autonomy. The military and West Pakistan saw it as an effort for separation. Mujibur Rehman was also arrested and imprisoned. 

1970 elections and the break point : In the 1970 elections, out of the total 300 seats, Mujibur Rehman’s Awami League came first with 160 seats, followed by Zulfiqar Ali Bhutto’s Pakistan People’s party winning 81 seats and other parties the remaining. The majority required was 151, and Awami League had won it. But the Pakistan military leadership and the West Pakistan political leadership combined to deny a legitimate. When the military establishment was dragging its feet, East Pakistan grew restive. In March 1971, Mujibur Rehman called for independence. The Pakistan President, Gen. Yahya Khan declared martial law in East Pakistan and ordered arrest of Mujibur Rehman. Then, the Pakistan military attacked East Pakistan and refugees flooded into India. Also, some of the East Pakistan forces, the Muktibahini had been trained by Indian armed forces and they attacked Pakistan military. The 1971 Bangladesh liberation war had begun. 

Following are the Consequences of Indo- Pakistan 1971 War: 

1. Creation of Bangladesh (Previously known as East Pakistan): Birth of a new nation. 

2. Myth of superiority of Islamic armies busted. 

3. Indo-Soviet Friendship. 

4. Military posture of Pakistan: With defeat of magnitude comparable to Stalingrad- Pakistan started covert aggression against India through militancy in Kashmir & Punjab. 

5. Bid to acquire Nuclear weapons. 

6. Signing of Shimla agreement in June 1972 for restoration of peace and order between the two states.