When the war broke out, IV corps went into action in the Agartala sector. At the start of the Dacca Campaign, Dacca was set as an objective for II Corps and IV Corps had been tasked to capture the fortress of Comilla. By 8 December, troops of the 57 Mountain Division and the IV Corps had already achieved their initial objectives of occupying the territory leading up to the Meghna. The only way across the river was over the Ashuganj Bridge, which very soon became a fortress where a Pakistani division had consolidated itself. The strategic importance of breaking down resistance at Ashuganj soon became apparent to Lt Gen Sagat Singh, leading the IV Corps, who realised that his troops could, with a push, threaten Dacca. Once a significant force had been built up, there was no recognisable enemy force between the helidropped force and Dacca. Ashuganj Bridge was the only bridge that spanned the huge Meghna River which at its narrowest point was more than 4000 yards wide. With his troops at Ashuganj, Singh however, realised his formation would be joining in the race to Dacca. As would later turn out, II Corps was held at Kushtia by Pakistani defences and did not make it to Dacca. However, Aerial photos also showed that the bridge had been destroyed and it would require the Army Engineers to construct a new bridge over the sprawling Meghna for Indian troops to advance. Anticipating high casualties in the attempt to take the bridge by force, Singh, along with Maj Gen B F Gonsalves, leading the 57 Mtn Div, made the decision to airlift the troops.
Brilliant in its conception, the idea was fraught with risks and dangers. The move had to go un-opposed, or at the worse, face minimal opposition from Pakistani troops north of Raipura. The Indian troops that were helidropped did not have artillery or armoured support. On the 9th, troops began to be airlifted to Raipura, south of the Ashuganj Bridge. Once this position was consolidated, the troops were to be airlifted to Narsingdi. From Narsingdi the road to Dacca would lie bare for IV Corps to take. To provide support for the heliborne troops, PT-76 Tanks were told to ford the Meghna River.
The Indian Air Force's operation was led by Gp Cpn Chandan Singh and utillised Mi-4 helicopters that had already been involved in the Sylhet air-lift on the night of 7 December. Through the night of 9 December, the IAF air-lifted the entire 311 Brigade. The first troops, numbering around six hundred were landed through the night of the 9th, immediately making contact with Pakistani troops north of Raipura. They however held their positions, with the IAF flying in reinforcements. Over the next 36 hours, over 110 sorties were flown. The Mi-4, which normally carried 14 troops, carried as many as 23 on board. The troops were initially airlifted to Raipura, south of the Ashuganj Bridge. At the same time as this operation was on, 73rd Brigade moved across Meghna on boats and riverine crafts.
After consolidating their positions at Raipura, the troops were helilifted to Narsingdi. After securing Narshingdi, Indian forces captured Daudkandi and Baidder Bazar on 14 and 15 December respectively, both with helicopter assault. From Narshingdi, the metalled road to Dacca lay undefended for IV Corps to take.
The Pakistani Army had left the roads to Dacca undefended moving their defences at the bridge-heads and defensive strong-points, expecting to hold the Indian Army at these positions long enough till the UN and international pressure halted the Indian advance. The Meghna Helibridge along with the Tangail Airdrop on 11 December ensured that these positions were by-passed, capturing the approaches to Dacca. Moreover, the Pakistani garrison at Ashuganj was effectively put under siege, facing the Indian Army at Brahmanbaria and at Raipura. The Tangail Airdrop a day later denied the Pakistani 93 Brigade the sanctuary of Dacca. Dacca now could only be defended by troops within the city.