Mitro Bahini (Bengali: মিত্রবাহিনী "Allied forces") was the alliance of the Indian Army and the then-East Pakistani Mukti Bahini (Bengali: মুক্তিবাহিনী "Liberation forces") that engaged the Pakistani forces in December 1971 during the Bangladesh Liberation War. The alliance provided the final blow to the already weakened Pakistan Army which surrendered thirteen days after the formal declaration of war.