India defeated Pak to liberate Bangladesh on Dec 16, 1971
India won the Bangladesh Liberation War against Pakistan on December 16, 1971, as the latter surrendered, resulting in the formation of Bangladesh. Since then, this day is celebrated as 'Vijay Diwas' in India and Bangladesh to commemorate the victory. While the war started between Bangladesh (then East Pakistan) and Pakistan in March 1971, India joined the battleground on December 3.