The Indo-Pakistani War of 1971 was a military confrontation between India and Pakistan that occurred during the Bangladesh Liberation War in East Pakistan from 3 December 1971 until the Pakistani capitulation in Dhaka on 16 December 1971. The war began with Pakistan's Operation Chengiz Khan which was preemptive aerial strikes on 11 Indian air stations, which led to the commencement of hostilities with Pakistan and Indian entry into the war for independence in East Pakistan on the side of Bengali nationalist forces, expanding the existing conflict with Indian and Pakistani forces engaging on both eastern and western fronts. Thirteen days after the war started, India achieved a clear upper hand, the Eastern Command of the Pakistan military signed the instrument of surrender on 16 December 19