WASHINGTON (Reuters) - Former Defense Secretary Robert McNamara died on Monday aged 93. He will be remembered most as the leading architect of America’s involvement in the Vietnam War.

“His age just caught up with him,” his wife Diana told Reuters. “He was not ill. He died peacefully in his sleep.”

McNamara also forged brilliant careers in industry and international finance, but his painful legacy remains Vietnam.

More than anyone else except possibly President Lyndon Johnson, McNamara became to anti-war critics the symbol of a failed policy that left more than 58,000 U.S. troops dead and the nation bogged down in a seemingly endless disaster in Southeast Asia.

Pundits came to call the conflict “McNamara’s War.”

With his slicked-back hair and rimless glasses, he became a familiar face to the nation as one of “the best and the brightest” assembled by President John Kennedy to form his policy-making brain trust.

But he left the Cabinet in 1968 under pressure from Johnson. By then disillusioned with the war, McNamara had criticized U.S. bombing of North Vietnam.

He spent the rest of his life trying to explain the U.S. role in Vietnam and apologizing for his mistakes, becoming the subject of an Academy Award winning documentary, “The Fog of War.” In the film, he discussed the difficult decision-making process during the Vietnam conflict as well as his Pentagon role in the Cuban missile crisis.

He first came to prominence as one of the “Whiz Kids” who revitalized Ford Motor Co. after World War Two and ended his public career as president of the World Bank.

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To those jobs, as well as defense secretary, the dynamic McNamara brought a driving ambition, a phenomenal memory for statistics and a quick, efficient grasp of facts.

McNamara was named defense secretary by Kennedy in 1961 and held the post longer than anyone before or since. He put his corporate organizational skills to use in trying to modernize the Pentagon during the Cold War.

BLOCKING COMMUNISM

But more and more, Vietnam became his focus. He made several fact-finding visits there in the early days of the U.S. military buildup, which Washington saw as the only way to block a communist takeover of Southeast Asia.

Theodore White, in his book “The Making of the President 1968,” said McNamara argued behind the scenes that the United States must not slip quietly into the war -- that the decision must be brought before Congress and the issue debated openly.

But Kennedy authorized a small-scale increase in troop strength and, after his assassination in 1963, Johnson bowed to pressure from his generals and began a major buildup that finally had more than 500,000 U.S. troops in Vietnam.

McNamara, convinced the war could be ended by Christmas 1965, threw his energies into effective execution of Johnson’s policies but miscalculated resistance to U.S. intervention both in Vietnam and at home.

In late 1967 he criticized the decision to bomb North Vietnam in retaliation for strikes on U.S. bases in the south. Johnson decided to remove him the following year, offering him the presidency of the World Bank.

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In 1971, the classified and highly sensitive Pentagon Papers, an official record of the U.S. involvement in Vietnam, were leaked to The New York Times.

In “McNamara: His Ordeal in the Pentagon,” Henry Trewhitt wrote that McNamara ordered the study to provide material that might help future generations avoid the mistakes made in Vietnam by intelligent, well-intentioned men like himself.

“When its contents broke in the press, however, his pleasure at seeing the record clarified was badly diminished by his shock that the two administrations (Kennedy and Johnson) had been deceitful about escalating the war,” Trewhitt wrote.

McNamara was quoted as saying: “My God, does anyone think I would have commissioned this if reasonable men could conclude that it shows me to be a liar?”

FIGHTING POVERTY

At the World Bank, McNamara conducted a crusade against poverty and directed an expansion of World Bank influence.

When he took over the independent United Nations affiliate in 1968, the bank was making only $1 billion in annual loan commitments to Third World nations. For the fiscal year ending June 30, 1981, his last day in office, it lent $11.5 billion.

McNamara shifted the emphasis of the bank’s lending from heavy industry to basics like farming and population control.

Robert Strange McNamara was born in San Francisco on June 9, 1916, to Robert James McNamara, a wholesale shoe salesman, and the former Clara Nell Strange, both of British ancestry.

A brilliant student, he graduated from the University of California in 1937 and earned a masters degree from Harvard Business School, where he joined the faculty in 1940.

While employed at the Pentagon in 1946, he and nine colleagues sent a prospectus to 20 firms, offering themselves as a “package deal” to any company needing managers.

Ford, then in financial trouble, accepted the 10, all statistics experts nicknamed “the Whiz Kids.” McNamara rose to the presidency of Ford by 1960.

On taking early retirement from the World Bank in 1981, McNamara kept an office in Washington where he joined dozens of corporate boards, including the Washington Post. He was also a member of the Trilateral Commission which promoted cooperation between Europe, Japan and the United States.

McNamara married Margaret Craig, a fellow student at the University of California, who died of cancer just before he left the World Bank. They had a son and a daughter.

And in 2004, at age 88, he married his Italian-born sweetheart, Diana Masieri Byfield in Assisi, Italy.