Leaflets and pamphlets played an important role in driving public opinion during the war. See also: Mukti Bahini
At first resistance was spontaneous and disorganized, and was not expected to be prolonged. But when the Pakistani Army cracked down upon the population, resistance grew. The Mukti Bahini became increasingly active. The Pakistani military sought to quell them, but increasing numbers of Bengali soldiers defected to the underground "Bangladesh army". These Bengali units slowly merged into the Mukti Bahini and bolstered their weaponry with supplies from India. Pakistan responded by airlifting in two infantry divisions and reorganizing their forces. They also raised paramilitary forces of Razakars, Al-Badrs and Al-Shams (who were mostly members of Muslim League, the then government party and other Islamist groups), as well as other Bengalis who opposed independence, and Bihari Muslims who had settled during the time of partition. On April 17, 1971, a provisional government was formed in Meherpur district in western Bangladesh bordering India with Sheikh Mujibur Rahman, who was in prison in Pakistan, as President, Syed Nazrul Islam as Acting President, and Tajuddin Ahmed as Prime Minister. As fighting grew between the army and the Bengali Mukti Bahini an estimated 10 million Bengalis, mainly Hindus, sought refuge in the Indian states of Assam and West Bengal. 
June – September
The eleven sectors
See also: List of sectors in Bangladesh Liberation War
Bangladesh forces command was set up on 11 July, with Col. M A G Osmani as commander in chief, Lt. Col. Abdur Rab as chief of Army Staff and Group Captain A K Khandker as Deputy Chief of Army Staff and Chief of Air Force. Bangladesh was divided into Eleven Sectors each with a commander chosen from defected officers of Pakistan army who joined the Mukti Bahini to conduct guerrilla operations and train fighters. Most of their training camps were situated near the border...