The defeat of the Pakistan Army in the 1971 Indo-Pakistan war owed much to Sam Manekshaw’s thorough preparation and careful timing of the Indian Army’s offensive.

The conflict arose from the results of the East Pakistan general election of 1970, decisively won by the Awami League led by Sheikh Mujibur Rahman. When the Pakistani President, Zulfikar Ali Bhutto, refused to yield the East Pakistan premiership to Mujibur, there were strikes and acts of non-co-operation in the capital, Dhaka. This led to the banning of the Awami League and the retaliatory formation of a civilian guerrilla group, the Mukti Bahini.

Then, on March 27, 1971, Mujibur’s spokesmen declared the national independence of Bangladesh (as East Pakistan was thenceforth to be known) and the predominantly West Pakistan Army intervened, resulting in an estimated ten million refugees seeking safety in India.

Manekshaw had become Chief of Staff of the Indian Army in 1969 and found himself embroiled in the East Pakistan crisis as soon as it broke out. After returning from an inspection tour of the affected border region in March, the Prime Minister Indira Gandhi asked him what the Indian Army could do to help. In typically frank fashion he replied: “Nothing,” going on to explain that the Army was unprepared but that, given time, he could prepare it.

At a Cabinet meeting a few days later he said that his troops would be ready in June, yet counselled against intervening at that point. He argued that the monsoon would seriously hinder the movement of troops and supplies and that the passes through the Himalayas would have to be protected against possible Chinese involvement, with the risk of India having to fight on two fronts. It would be better, he advised, to wait for the monsoon to end and for snow to seal the mountain passes. Those who demanded an immediate invasion pointed out that India could not handle more refugees. Thousands of East Pakistan dissidents — including many intellectuals — were being killed by Pakistani troops and police in an attempt to crush the rebellion, sending waves of refugees into India every day.

Despite stiff resistance from Cabinet members, Manekshaw stood his ground, warning of a debacle if troops, artillery and vehicles floundered in the monsoon mud. He offered to resign but Indira Gandhi wisely let him have his way.

His obduracy, which had often led him into conflict with politicians and senior bureaucrats, doubtless saved India from something approaching the humiliating war with China in 1962. Yet Manekshaw’s insistence on thorough planning for the invasion induced a whispering campaign that he lacked the stomach to fight. Some Cabinet ministers wanted to sack him and order immediate war — just as the monsoon was about to break.

In the event, on December 3, 1971, Pakistani aircraft were considered to have violated the Indian frontier and war began. When Indian troops finally crossed the border of East Pakistan they were well supplied and trained, scarcely pausing in their march on Dhaka. In contrast, the West Pakistan troops were demoralised and many already resigned to defeat. Manekshaw’s delay had also allowed time to arm and train the guerrillas of the Mukti Bahini, who had seized control of much of the countryside and harassed the Pakistani troops until they withdrew into garrison towns, all of which were cut off from the main command in Dhaka.

Thousands of Pakistanis surrendered without a fight, resulting in the largest single capitulation of troops since the end of the Second World War. On December 16 General Abdullah Khan Niazi, in command of Pakistan’s Eastern Army, formally surrendered in a public ceremony and was held as a prisoner of war.

Manekshaw became an overnight hero. The war changed the map of South Asia and established India as the regional superpower; it might so easily have turned out differently, had Indira Gandhi’s Cabinet had its way.

In January 1973, two weeks before his retirement after four decades of military service, Manekshaw was promoted to the ceremonial rank of field marshal — only the second Indian to hold it. He was so popular that Indira Gandhi asked him, apparently seriously, if he was planning to take over the country. He pointed to his long nose and told her he did not use it to poke into other people’s affairs.

Sam Hormusji Framji Jamshedji Manekshaw was born in Amritsar, Punjab, in 1914. He was born a Parsi, a small, prosperous community that emphasises education. After attending Sherwood College in Nainital, he expected to follow his two older brothers to England for higher education but his father, a doctor, decided that at 15 he was too young. He went instead to Hindu Sabhya College in Amritsar and while there decided on an army career.

He was one of the first cadets accepted into the Indian Military Academy at Dehra Dun, which trained Indians for commissions in the British Indian Army. In the Second World War he served in Burma and was badly wounded in the stomach during an infantry assault near the Sittang river and was awarded the Military Cross.

After the Partition of India in 1947 he became one of the first Indian officers to command Gurkha soldiers who had chosen to serve in the new Indian Army and developed a deep affection for them. He was a fluent Nepalese speaker, and a Gurkha family looked after him in his retirement bungalow in Coonoor, where he was frequently visited by officers of his former regiment. He was quoted as saying: “If a man says he is not afraid of death, he is either lying or he is a Gurkha.”

He had a great love for his 1958 Sunbeam Rapier car, which he took with him everywhere: to Kashmir, Bombay and to Calcutta when he was Commander of the Eastern Army. At 90, he would still sometimes ask to be driven around in it.

Just before Partition he had sold a James motorcycle to his friend Major Yahya Khan, who moved to Pakistan and became Chief of the Army Staff there — a job he lost after Manekshaw’s triumph in Bangladesh. Manekshaw said Yahya never paid him for the motorcycle, “but he made up for it by giving me East Pakistan”.

Manekshaw’s wife, Silloo Bode, whom he married in 1939, died in 2001. He is survived by two daughters.

Field Marshal Sam Manekshaw, MC, Chief of Staff, Indian Army, 1969-73, was born on April 3, 1914. He died on June 27, 2008, aged 94