1971, civil war erupts in Pakistan, pitting the West Pakistan army against East Pakistanis demanding autonomy and later independence. Fighting forces an estimated 10 million East Pakistani civilians to flee to India
Pakistan launched pre-emptive air strikes on 11 Indian airbases on 3 December 1971, India invades East Pakistan in support of the East Pakistani people, and attacks the West Pakistan Air Force, Army and Navy in East Pakistan and attacks West Pakistan. The war is no contest lasting just 13 days with decisive Indian victories on land, in the air and at sea, Pakistani army in East Pakistan surrenders at Dhaka and its army of more than 90,000 become Indian prisoners of war.
East Pakistan becomes the independent country of Bangladesh on 16 December 1971.
The war was devastating in its brutality but there are a range of estimates for the exact number of people killed - government figures estimate as many as three million died. Other studies suggest 300-500,000 perished.
The war was also devastating defeat for Pakistan on 17 December 1971 it lost half it's land area, lost half its population and a significant portion of its economy to the new country of Bangladesh.
Pakistan lost half its navy, a quarter of its air force and its army suffered 33,000 casualties.