Eastern Sector :The eastern sector comprised the area east of the Meghna in the destricts of Sylhet, Brahmanbaria, Comilla and Chittagong, and Chittagong Hill Tracts. The approach to Dacca lay across the Meghna, a river of great width ranging from 4,000 to 4,500 yards. It was spanned only by the railway bridge at Ashuganj, which was about 2,950 feet long. The terrain, except the hill tracts, is generally low-lying and waterlogged by paddy fields. Like the rest of Bangladesh, it is interspersed with numerous rivers and drainage channels. Cross-country movement is generally difficult till the first week of December. Since the rivers frequently change course and cause bridging problems, ferries are the only reliable means of crossing.
Sylhet district is pocked with numerous haors bheels, perennial lakes with several feeder streams, and extensive marshes surrounded them. The landscape is broken by high mounds called tillas, ranging from 100 to 200 feet. These tillas are surrounded by lowlying langai land which remains waterlogged for nine months a year.
In Comilla district, the Lalmai Hills extend north to southwest of Comilla town. These low hills are about 16 kilometres long and four wide and have numerous elevations covered with low vegetation. The average height of the range is about 225 kilometres.
As for road and rail communications on the Indian side, a single-track, metre-gauge railway took off from the trans-Assam artery at Lumding and terminated at Dharampur after running a considerable distance close to the Indo-Pakistani border. The stretch between Karimganj and Dharampur was prone to disruption by Pakistani saboteurs. Several attempts were made to blow up the track at various points, but vigorous security measures, including regular trolley patrols, searchlight specials and tracker dogs, kept trains running throughout the period of preparation for and conduct of the war.
Laksham was the hub of the road and rail communications to Chittagong. The capture of Brahmanbaria could cut off all the Pakistani forces in the eastern sector…
On the East Pakistan side, a similar single metre gauge track ran north to south connecting Sylhet with Chittagong. For most of its distance it ran close and parallel to the international border. Besides being connnected across the Meghna with Dacca and Mymensingh, it fed the river ferries of Chandpur and Noakhali. The strategic bottleneck along these communication arteries was the Brahmanbaria area, as the Ashuganj bridge connected the Dacca and Mymensingh sectors with the eastern sector. Laksham was the hub of the road and rail communications to Chittagong. The capture of Brahmanbaria could cut off all the Pakistani forces in the eastern sector, especially the Sylhet and Maulvi Bazaar garrison, and the capture of Laksham would cut off the Comilla garrison.
Similarly, on the Indian side, an arterial road connecting Assam with Tripura ran north and south from Silchar to Belonia via Teliamura, a communication centre which fed Kamalpur, Khowai, Agartala, Sonamura and other border towns. In addition, a road running parallel to the international border, particularly south of Agartala to Chanddegram, had been newly constructed and improved to enable the quicker deployment of troops. Agartala was also connected with Sabrum, a border town overlooking Chittagong Hill Tracts. Various laterals connected the Silchar-Belonia artery with the Agartala-Sabrum road for flexibility in diverting traffic.
Most of the Indian fields were too close to the border, Agartala airfield being within the range of small arms in Pakistani posts overlooking the runway.
On the East Pakistan side, the main road artery ran parallel to the railway from Sylhet to Chittagong. Various feeder roads linked the border towns and the river ferries. It was easy to link the two road systems at a chosen point of entry. On the other hand, the railway system could be linked only at Latu, opposite Karimganj. The road and rail tracks on the Pakistan side ran over an embankment four to eight feet high. A large number of bridges and culverts were destroyed by Freedom Fighters or the retreating Pakistanis. Road construction was difficult because materials were not available locally. Decking of railway bridges did not help as the width of the track did not allow passage of heavier vehicles.
The operational airfields available to Pakistan were at Dacca, Sylhet, Shamshernagar, Comilla, Chittagong and Cox’s Bazaar. Most of them had been built by the Allies in the Second World War to serve the Burma theatre and the Pakistani Government had kept them in good condition. They could handle Sabrejets. On the Indian side, Silchar airfield was available to jets while Kamalpur, Khowai and Kailashabar were fit only for transport planes. Most of the Indian fields were too close to the border, Agartala airfield being within the range of small arms in Pakistani posts overlooking the runway.
This was a clever ruse indeed as it confused Indian intelligence for quite a while with the same units appearing in their Orbat in the eastern and western wings at the same time.
The Pakistani forces in the sector were built up gradually as the insurgency mounted. Originally, 53 Infantry Brigade Group, of 14 Infantry Division located at Comilla, controlled the whole eastern sector with a battalion each at Sylhet and Chittagong. When Pakistan 9 Infantry Division was inducted into the east wing on the outbreak of hostilities, it was made operationally responsible for the area east of the Meghna and 53 Infantry Brigade Group came under its command. The broad deployment of the division before the monsoon was 313 Infantry Brigade in the area of Sylhet, 117 Infantry Brigade at Comilla, and 53 Infantry Brigade in the Chittagong area. 27 Infantry Brigade of 9 Infantry Division was deployed in Mymensingh and placed under the command of 14 Infantry Division, then operationally responsible for the area, including Dacca and Jessore.
With the growing intensity of the insurgency and Niazi’s concept of holding the border in strength, the troop requirements increased. Niazi accordingly raised 202 Infantry Brigade at Sylhet, pulling 313 Infantry Brigade southward to the general area of Maulvi Bazaar. 27 Infantry Brigade reverted to the eastern sector and was deployed in the general area of Brahmanbaria and Akhaura. These three brigades in the northern half of the sector were grouped under Headquarters 14 Infantry Division commanded by Maj Gen Abdul Majid. With 117 Infantry Brigade at Comilla in the southern half of the sector, 53 Infantry Brigade was pulled back to the general area of Laksham and Feni, and the newly raised 97 Infantry Brigade at Chittagong was placed under the command of Headquarters 39 Infantry Division, raised on an ad hoc basis, under Gen Rahim Khan.
None of these brigades had full combat power because they consisted of one or two regular battalions, one “Azad Kashmir” unit and a battalion strength of paramilitary forces. The supporting fire units were ad hoc collections of guns and mortars, but even those were deployed in penny packets. To conceal this weakness, non-regular Ranger and Scout units were given the designations of regular infantry battalions located in the western wing.
This was a clever ruse indeed as it confused Indian intelligence for quite a while with the same units appearing in their Orbat in the eastern and western wings at the same time. The puzzle could not be solved till the very end of the conflict. It is difficult to understand why, in undertaking this reorganisation, Niazi moved Headquarters 9 Infantry Division from its original formation to the Jessore sector and kept Headquarters 14 Infantry Division in this region commanding brigades belonging to another division. Gen Sagat Singh, General Officer Commanding IV Corps, was operationally responsible for the eastern sector. His task was initially to ensure the security of rail and road communications in the sector during the administrative and troop buildup in the region, as also to provide protection to administrative installations, airfields and Air Force establishments under development in the corps zone of responsibility. This was to be achieved by denying the enemy ingress into Tripura and Silchar district, with particular emphasis on the security of Agartala town and its airfield.