Before his arrest on the night of 25 March 1971, Mujib issued a call for Bengalis to fight for their independence; declaration of independence was proclaimed from Chittagong by members of the Mukti Bahini—the national liberation army formed by Bengali military, paramilitary and civilians. The East Bengal Regiment and the East Pakistan Rifles played a crucial role in the resistance. Led by General M. A. G. Osmani and eleven sector commanders, the Bangladesh Forces waged a mass guerrilla war against the Pakistani military. They liberated numerous towns and cities in the initial months of the conflict. The Pakistan Army regained momentum in the monsoon. Bengali guerrillas carried out widespread sabotage, including Operation Jackpot against the Pakistan Navy. The nascent Bangladesh Air Force flew sorties against Pakistani military bases. By November, the Bangladesh forces restricted the Pakistani military to its barracks during the night. They secured control of most parts of the countryside.and the independent state of Bangladesh was officially declared by the Awami League's government-in-exile in Mujibnagar. Mujib's trademark "Joy Bangla" ("Victory to Bengal") salute became the rallying cry of Bengali nationalists, who mobilised to form the Mukti Bahini guerrilla force, which received training and equipment from the Indian government. Indian intervention at the height of the liberation war would eventually lead to the surrender of Pakistani forces and the establishment of the Bangladeshi state on 16 December.