Excerpt taken from "The Encyclopedia of Land Warfare in the 20th Century", Part 5, Asian Wars of Imperial Succession, Brigadier Shelford Bidwell, Pages 164-173, Leisure Books, Salamander Books Ltd 1977, 27 Old Gloucester St, London WC1N 3AF, UK
This time the war centred round East Pakistan, which under political oppression and economic exploitation was becoming increasingly hostile to rule from West Pakistan. Instability in Bengal increased to a point at which the Indian government could not ignore. Humanity demanded military action, and self-interest argued that if Pakistan's most economically productive wing was detached, the aggressive West Pakistanis would have their economic teeth drawn and the danger from that quarter would be substantially a reduced. Politically the moment for military action had to be nicely judged, for if the Chinese chose to intervene on Pakistan's behalf there could be a war on three instead of two fronts, which would be embarrassing, for although reorganisation had produced a balanced deployment and a reserve, India's land defences were stretched in an enormous arc from Raiputana round to Assam. In any case some mountain troops would have to be pulled south from the Himalayan and north~eastern sectors for a campaign in Bengal. The risk was taken, for China was in the throes of becoming respectable as an international power and, moreover, its dangerous frontier was now the one with Soviet Russia, of whom it was secretly terrified.
As regards relative strengths, India had 24 divisions plus a number of armoured and infantry brigades (two of parachute troops) and its tank strength had been augmented by 450 Russian T-55s and T-56s and 300 Indian-built Vijayantas of Vickers design. Morale was high and the quality of the high command outstanding. The army was supported by an efficient air force equipped with Mikoyan-Gurevich MiG-215, Sukhoi Su-75, some serviceable home-constructed Folland Gnat interceptors and some old British Hawker Hunters and English Electric Canberras.
Against this the Pakistani army could muster only 12 infantry and two armoured divisions, plus an armoured brigade and anair force weaker and less efficient than India's. As basic material Pakistani troops were excellent, but a corrupt regime had rotted the army's leadership and morale.
The war on two fronts took place as predicted. Pakistan attacked in the west in the hope of drawing some Indian strength away from the defenders of Bengal. The events of 1965 repeated themselves: very stiff fighting and limited gains and losses by both sides. But the Indians held firm in the west against heavy pressure, first parrying and then riposting with limited offensives. The operations of 1971 finally dispelled any vain dreams that the 'sword-arm' of old India could, despite its numerical inferiority, sweep aside the armies of the effete Hindus and win another battle of Panipat outside the walls of Delhi. Not an Indian brigade had to be moved West. General Jagjit Singh Aurora's daring concentric attack on East Pakistan went forward uninterrupted and on 16 December he received the surrender of the Pakistani commander in Dacca.
A close study of this campaign will edify military students for a long time to come. Bengal, now BanglaDesh (literally Land of Bengal), is an eminently defensible country cut up by rivers five miles wide and obstructed by marshes. The Indian plan was a masterly combination of airborne, guerrilla and conventional forces, based on complete mobility and the bypassing of all centres of resistance. The advance was not held up for bridging operations; troops and guns were ferried over the rivers by helicopter, and 'supply and transport' was by air, boat, canoe or country cart as suitable. An astonishing momentum was maintained from start to finish - it was a Blitzkrieg without tanks.