The nature of these systematic purges enraged the Bengalis, who declared independence from West Pakistan to establish the new nation of Bangladesh in the erstwhile region of East Bengal.

President Yahya Khan flew to Dacca to hold talks with Mujibur Rahman, then leader of the Awami League, in March and was later joined by Bhutto, whose party had secured the second-largest share of seats (81 out of 300) in the general elections.

[28] Requirements for success:[28] The designated centres of offensive operations under that plan were Dhaka, Khulna, Chittagong, Comilla, Jessore, Rajshahi, Rangpur, Saidpur and Sylhet, areas where West Pakistani army units were concentrated.

Although the plan did not specify the time needed to subdue East Pakistan, it was assumed that after the arrest of the political leadership and disarming of the Bengali military and paramilitary units, civilians could be terrorised into submitting to martial law within a week.

These four brigades had 12 infantry battalions[30] (regiments normally had 915 soldiers each) containing purely West Pakistani personnel (mainly hailing from Punjabi, Baluch, Pathan and Sindhi background) before 25 March 1971.

Mozumdar, who had refused to fire on Bengali civilians blocking the unloading of MV Swat, was relieved of his post on 24 March by Gen. Khadim himself on the pretext that he was needed to address 2 EBR at Joydebpur and Brig.

[citation needed] Denied permission by General Hamid to disarm the regular Bengali army units en masse before the crackdown,[45] the Pakistani command employed other ploys to minimise the threat of these formations.

Rumor spread in the city after dusk that Yahia Khan had left and Awami League volunteers put up makeshift barricades in the streets, but these did not cause any significant delay to Pakistani troop movements.

Chittagong housed the only oil refinery in East Pakistan, had a large fuel depot, was the largest seaport and MV Swat, with 9000 tons of arms and ammunition was in port.

Some plain cloths Commandos were in the city[36] The Pakistani Navy (under Commodore Mumtaz) had 300 troops and the PAF had an unknown number of personnel at the naval base and at the airport respectively.

Course of events: The daytime witnessed nothing unusual, Pakistani and Bengali troops continued normal activities, while civilians barricaded streets to impede army movements.

Captain Rafiq sent an EPR Machine gun platoon under Subadar Musa, with a mortar and rocket launcher to delay the Pakistani column near Kumira, 12 miles north of Chittagong.

By 11:30 pm Captain Haroon had taken control of the wing, put Pakistani personnel in jail, and had signalled EPR troops in border areas to move to Chittagong by 3:30 am.

Around 2:30 pm local Awami League leader M. A. Hannan made a declaration of Independence on behalf of Sheikh Mujibur Rahman from the Kalurghat Radio station, which was not picked up by many people.

Half the convoy was outside the ambush firing range and Pakistanis, commanded by Major Amzad Hussain (Bengali −2IC 24 FF) fought back, and a 2-hour long battle ensued.

General Mitha arrived in Chittagong around midday via Helicopter and planned to send a commando platoon from 2 SSG under Lt. Col Sulayman to link up with 20 Baluch before going on to locate Brig.

Ansari formed a task force of 2 tanks, one infantry battalion and mortars to hold the port area, supported by the 2 SSG commandos and naval ships.

Captain Aziz took position on the southern end of Keane Bridge in Sylhet city, cutting off-road access to areas south of the Surma river.

The CO then spread out his forces and set up outposts at the Town Police HQ, VHF Radio Station, Telephone exchange and District school, and disabled the phone and telegraph lines.

Major Osman met with political leaders, government officials and at 2:30 pm raised the Bangladesh flag at EPR HQ – signalling the start of revolt.

All EPR troops at the border were ordered to Chuadanga on the same day, while Major Osman sent a letter to Lt. Col. Jalil (CO 1 EBR – Bengali), then at Chaugacha with his battalion, informing him of the Pakistani crackdown and requesting him to take command.

After a fierce 4 hour battle causing severe casualties on both sides, Pakistani forces left the town and took up a strong defensive position around the cantonment at Sapura, using minefields and barbed wire to beef up the place.

Bengali fighters launched several attacks on the cantonment between 6–10 April, and although the Pakistanis were ultimately confined in an area only 800 yards square, the Punjab regiment managed to survive.

Col. Hakeem fortunately managed to avoid the trap by calling out Lt. Rafiquddin Sarkar, 3 EBR platoon leader and keeping him in his jeep before opening fire, and returned to Saidpur after a firefight erupted.

[153] The significance of the deployment of the Bengali forces in the west, south and north of Saidpur in a semicircle, with the road east to Rangpur open, was not lost to the Pakistani commanders.

Gen. Niazi, who took command of Pakistan forces in Bangladesh on 11 April, obtained a brief from Gen. Raja (the departing GOC) and implemented the following strategy:[155] Against this strategy Bengali field commanders opted to go with "holding as much area for as long as possible",[156] The Bengali leadership hoped to keep the Pakistanis confined into the cities, while the Bangladesh government in exile sought diplomatic recognition and the resistance prepared for eventual guerrilla warfare[157] and awaited the expected Indian military intervention.

The Bangladesh government in exile was formed by the Awami League leadership on 17 April at Meherpur in Kushtia, which confirmed Col. Osmani as commander of Mukti Bahini (regular armed forces and insurgents) under the authority of Prime Minister Tajuddin Ahmad.

The temporary presence of this large foreign population created economic (the cost of feeding, housing and medical care), social (tensions between locals and refugees) and national security (arms falling in the hands of Mizo and Naga rebels) concerns for India.

[citation needed] The deaths included Col. Badiul Alam, Lt. Col. MA Qadir, Lt. Col. S. A. Hai, Lt. Col. M. R. Choudhury, Lt. Col. (Dr.) Abul Fazal Ziaur Rahman, Lt. Col. N. A. M. Jahangir and another dozens of senior majors who were executed by April 1971.

[citation needed] The eventual strain of combating the insurgency caused Pakistan to attack India on 3 December 1971, with the objective to stop Indian support for the Mukti Bahini.