§ indicates events in the internal resistance movement linked to the Indo-Pakistani War. ‡ indicates events in the Indo-Pakistani War linked to the internal resistance movement in Bangladesh.
The 57th Mountain Division had been given the task of advancing on Dhaka from the East and North East. On 5 December, the 57th captured its first objective, the Pakistani fortified town of Akhaura. From here, they were supposed to advance to the town of Daudkani and then Feni, however IV Corps redirected the division to attack and seize Brahmanbaria. This was done to cut off the Pakistani 202nd and 313th Infantry Brigades in Sylhet which had come under pressure from the advance of other IV Corps units further north of Sylhet. Then, the objective of the 57th became to secure the eastern bank of the Meghna and capture Bhairab Bazar on the western bank before advancing on Dhaka.[1][2][3]
Capture of Brahmanbaria
73 Mountain Brigade, under the 57th, was given the task of capturing Brahmanbaria. 73 Mtn Bde, along with assistance from the maneuver elements of 311 Mtn Bde (namely, 14 Guards) enveloped Brahmanbaria by 7 December. Elements of the Pakistan 27th Infantry Brigade, noting that they had been enveloped, chose to withdraw from Brahmanbaria. This was also due in part to the CO of the 27th, Brigadier Saadullah Khan, ordering a general retreat to the fortified positions at Ashuganj. With Brahmanbaria now captured with no resistance, the next target of the 57th became Ashuganj.[1]
Orders of battle
Indian Army
During the advance from Brahmanbaria to Ashuganj, and the air assault operation that followed, the order of battle was thus:[1]
19th Battalion, Rajputana Rifles (detached from 73 Mtn Bde and attached to 311 Mtn Bde on 11 Dec)
15 Engineer Regiment
Indian Air Force
The Indian Air Force had attached multiple helicopter units to the various Indian Army offensive corps before the war. The role of these units was to ferry supplies and assist the Corps Commanders in attaining their objective. The 2 helicopter units, under Group Captain Chandan Singh that performed this air assault were as follows:[4][2]
Defending against Lt. Gen. Sagat Singh's IV Corps was the Pakistan Army's 14th Infantry Division. Defending Ashuganj and Bhairab Bazar would only be the 27th Infantry Brigade. Its order of battle was thus:[1]
The objective for the 57th Mountain Division in what became the first phase on their advance across the Meghna were as follows, in the order that follows:[1]
Capture Ashuganj
Capture and cross Coronation Bridge
Capture Bhairab Bazar
Advance toward Dhaka
Second phase
As the Pakistanis, while withdrawing from Ashuganj demolished Coronation Bridge, rendering it unusable, the objectives - for what became the second phase - were as follows, in the order that follows:[1]
Use civilian fishing boats to cross Meghna under cover of darkness
Advance toward Bhairab Bazar and surround it
19 Rajputana Rifles to link up with 4 Guards at Narsingdi
Following this, the 57th was to begin the advance on Dhaka.
First phase
Battle of Ashuganj
What became, effectively, the "First Phase" of the Meghna Crossing, was the advance to Ashuganj. The advance was spearheaded by 73 Mtn Bde, supported by tanks from 63 Cavalry. However, the Pakistani 27 Infantry Brigade had turned Ashuganj into a fortress. The spearhead of 18th Battalion, Rajput Regiment and 10th Battalion, Bihar Regiment, supported by a squadron of PT-76s from 63 Cavalry reached the outskirts of Ashuganj at 1300hrs on 9 December. They arrived to find that the bridge had already been blown up ahead of the arrival of Indian troops and a significant force of the Pakistani 27 Infantry Brigade was camped at Ashuganj to defend it. In the fighting, 44 Indian soldiers were killed and 4 PT-76s destroyed or damaged, as against 29 Pakistani soldiers. However, by the morning of the 10th, the Pakistanis had retreated from Ashuganj on the last remaining boats to Bhairab Bazar.[1][2]
Second phase
9 December - air assault
It had become clear to Gen. Sagat Singh by 7 December, that an air assault operation would be required to cross the Meghna. Inspired by the airlift/air assault operations that had surrounded Sylhet between 6 and 9 December, he ordered plans to be drawn up for a similar operation to cross the Meghna. The engineers of 15 Engineer Regiment and Group Captain Chandan began to plan the operation. They identified possible landing grounds and, with the help of the Mukti Bahini, began to mark them with modified torches. Mukti Bahini fighters set up these modified torches in paddy fields at Raipura (the DZ) in the hours before the helicopters landed.[5] At 1300hrs on the 9th, as 18 Rajpur and 10 Bihar entered Ashuganj, 4 Guards was recalled from the lines at Ashuganj to the stadium at Brahmanbaria. Sometime in the evening, they began to board Mi-4 helicopters bound for Raipura. According to Major Chandrakant Singh, an officer in 4 Guards at the time, the 14 Mi-4s were escorted by 2 Folland Gnat figters and landed at their DZ without any issue.[3]
The Mi-4s had had to land, in the pitch dark, on dimly lit fields. As such, upon landing, Flying Officer D. S. Shaheed got out and began to mark the DZ with wheat flour.[3] At the time, there was a fear that the two brigades of the Pakistani 14th Inf Div at Bhairab Bazar would spot the landings and overwhelm 4 Guards before they'd had a chance to regroup. However, no such counterattack materialised.[1] By 4 am, the helicopters had conducted about 50-60 sorties and had moved all ~700 men of 4 Guards, along with an artillery battery from 82 Light Regiment, to Raipura.[1][3][2] After the war, it was revealed by Pakistani POW's that - upon hearing the sound of helicopters - it was assumed that an entire Indian brigade had been landed to their rear and as such, they were not allowed to move out of Bhairab Bazar.[1]
9 December - 19 Punjab crosses the Meghna
At the same time as 4 Guard was moving, 19 Punjab had moved further south on the eastern bank of the Meghna to the village of Charlalpur. From here, using commandeered civilian fishing boats, they crossed the Meghna under cover of darkness, with the entire battalion having crossed within a few hours. They immediately moved to surround the Pakistani forces at Bhairab Bazar, as there were fears of an imminent Pakistani attack on 4 Guards.
10-11 December - advance on Narsingdi
4 Guards had reorganised and regrouped by 0400hrs, following the landings at Raipura. After patrols had scouted out Pakistani positions on the road to Narsingdi, 4 Guards began their attack on Narsingdi railway bridge. Their objective was to keep the Pakistani defenders occupied and unable to detonate the explosives on the bridge. By the end of the day, the battalion had secured a river crossing point on the western bank of the Meghna and had captured the railway bridge at Narsingdi. It materialised that the Pakistanis had left behind only 1 platoon of paramilitary to defend Narsingdi, with the Army moving across the Lakhya River to bolster the defence of Dhaka. As such, 4 Guards faced no casualties and wiped out or captured the platoon with ease.[1][2][3]
As 4 Guards was fighting in Narsingdi, the Mi-4s were carrying out multiple sorties to land 10 Bihar at Raipura. From there, 10 Bihar (along with a battery of medium artillery which was also landed) moved west to assist in the capture of Narsingdi. Simultaneously, on the 11th, 19 Raj Rif had been crossing the Meghna on boats and linked up with 4 Guards by midday, being transferred into 311 Mountain Brigade.[1]
12 December - advance towards Dhaka
With 27 and 313 Infantry Brigades successfully isolated at Bhairab Bazar, the entirety of 311 Mountain Brigade would be airlifted into Raipura by the 14 Mi-4s which flew over 200 sorties between 9 and 13 December. By 0800hrs, 4 Guards - the forwardmost unit of 311 Mountain Brigade - was only 12 kilometers short of Dhaka. They encountered Pakistani positions on the east of the Lakhya River, but these were quickly overwhelmed. By the end of the 12th, 311 Mountain Brigade was within artillery range of Dhaka.[1][2]
Aftermath
Operation Cactus Lilly, combined with the success of the Tangail Airdrop and its consequences, meant that the Indian Army had reached the gates of Dhaka by 12 December. As Lt. Gen. A. A.K. Niazi realised that Dhaka was surrounded, he and the then Governor of East Pakistan, began the diplomatic process of organising a ceasefire and then a surrender. Due to this, the Indian Army's forward units received the order to advance on Dhaka slowly, to give the Pakistanis time to surrender. Regardless, the Indian Army's first heavy artillery reached artillery range by 14 December. On the same day, the Indian artillery began a bombardment of Dhaka Cantonment and the Pakistani positions at Dhaka. By the 16th, the war was over and the Pakistani forces would sign an unconditional surrender.[1][5]
Bangladesh
Pakistan
