Robert McNamara, the long-serving US Secretary of Defence whose name became synonymous with American failures and excesses in Vietnam, has died in his sleep at the age of 93.

His wife, Diana, said that McNamara passed away at home in Washington at 5.30 am today.

Cerebral and arrogant, Mr McNamara started his working life as an academic at the Harvard Business School before a stint in the armed forces during the Second World War.

In 1946, he joined the Ford Motor Company, one of a number of "whiz kids" hired to help restructure it and stem its losses. He was so successful that in November 1960, at the age of 44, he was named president of the entire company, the first man in that post who was not a member of the Ford family.

But within weeks of securing one of the most powerful jobs in American industry, McNamara was offered a Cabinet-level post in the incoming Kennedy administration. He turned down the post of Treasurer but agreed to become Secretary of Defence and used the same skills deployed at Ford to reshape the US military machine to respond to the threat of the Cold War.

While at the Pentagon, he became fundamentally associated with the Vietnam War - "I don't object to it being called McNamara's war," he wrote in 1964 – and was responsible both for the devastating bombing campaign of the North and for continuing to pour reinforcements into the country even after he became convinced that American could never win.

By 1968, with President Johnson refusing to heed his call for Americans to withdraw, McNamara left the Pentagon on the verge of a nervous breakdown and became president of the World Bank, where he devoted his energies over the next dozen years to helping the world's poorest nations – penance, his critics said, for his actions in Vietnam.

An intensely private person, McNamara for many years declined to write his memoirs, but he finally began to open up in the early 1990s.

He told Time magazine in 1991 that he did not think the bombing of North Vietnam – the biggest bombing campaign in history up to that time – would work but he went along with it "because we had to try to prove it would not work, number one, and (because) other people thought it would work".

Finally, in 1993, after the Cold War ended, he undertook to write his memoirs because some of the lessons of Vietnam were applicable to the post-Cold War period "odd as though it may seem."

In Retrospect: The Tragedy and Lessons of Vietnam appeared in 1995. McNamara disclosed that by 1967 he had deep misgivings about Vietnam – by then he had lost faith in America’s capacity to prevail over a guerrilla insurgency that had driven the French from the same jungle countryside.

Despite those doubts, he had continued to express public confidence that the application of enough American firepower would cause the Communists to make peace. In that period, the number of US casualties – dead, missing and wounded – went from 7,466 to over 100,000.

"We of the Kennedy and Johnson administrations acted according to what we thought were the principles and traditions of our country. But we were wrong. We were terribly wrong," said McNamara.

The best-selling mea culpa renewed the national debate about the war but prompted bitter criticism against its author.

"Where was he when we needed him?" a Boston Globe editorial asked. A New York Times editorial referred to McNamara as offering the war’s dead only a "prime-time apology and stale tears, three decades late".

McNamara re-examined the themes of Vietnam in a 2003 documentary The Fog of War: Eleven Lessons from the Life of Robert S.McNamara.

With the US in the first year of the war in Iraq – under a Defence Secretary, Donald Rumsfeld, many compared with McNamara – it became a popular and timely art-house attraction and won the Oscar for best documentary feature.

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