WASHINGTON – Robert S. McNamara, the brainy Pentagon chief who directed the escalation of the Vietnam War despite private doubts the war was winnable or worth fighting, died Monday at 93.

McNamara revealed his misgivings three decades after the American defeat that some called “McNamara’s war.”

“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,” McNamara told The Associated Press in 1995, the year his best-selling memoir appeared.

McNamara died at 5:30 a.m. at his home, his wife Diana told the AP. She said he had been in failing health for some time.

Closely identified with the war’s early years, McNamara was a forceful public optimist. He predicted that American intervention would enable the South Vietnamese, despite internal feuds, to stand by themselves “by the end of 1965.” The war ground on until 1975, with more than 58,000 U.S. deaths.

Lawyerly and a student of statistical analysis, McNamara was recruited to run the Pentagon by President John F. Kennedy in 1961 from the presidency of the Ford Motor Co. – where he and a group of colleagues had been known as the “whiz kids.”

He stayed in the defense post for seven years, longer than anyone else since the job’s creation in 1947. He left on the verge of a nervous breakdown and became president of the World Bank. In the new post, he threw himself into the intricacies of international development and argued that improving lives was a more promising path to peace than building up arms and armies.

McNamara was a distinctive figure, with frameless glasses and slicked-back hair. Anti-war critics ridiculed him as an out-of-touch technocrat and made much of the fact that his middle name was “Strange.” Simon and Garfunkel worked his name into a ditty about an overbearing government, and he once had to flee an appearance at Harvard through underground utility tunnels.

By the end of his Pentagon tenure, McNamara had come to doubt the value of widespread U.S. bombing, and he was fighting with his generals. President Lyndon Johnson lost faith or patience in him; McNamara would later write that he didn’t know if he quit or was fired.

In the Kennedy administration, McNamara was a key figure in both the disastrous Bay of Pigs invasion of April 1961 and the Cuban missile crisis 18 months later. The missile episode was the closest the world came to a nuclear confrontation between the Soviet Union and the United States, and historians have pointed to McNamara’s role in steering internal debate away from a U.S. airstrike.

Reticent, McNamara long resisted offers to give a detailed accounting of his role in Vietnam. His son, who had protested the war his father helped to run, once said it was not within McNamara’s “scope” to be reflective about the war.

McNamara’s eventual mea culpa won him admiration from some former opponents of the war. Others said it was not enough, and three decades too late.

“Where was he when we needed him?” a Boston Globe editorial asked.

Ted Sorensen, a speechwriter and adviser who worked with McNamara in both the Kennedy and Johnson administrations, said the criticism missed the mark.

“Most military chieftains – presidents or Cabinet members or otherwise – don’t admit error, ever,” Sorensen said. “At least Bob had the courage and commitment to truth to put out that he was wrong and why it was wrong so that we could all learn the lessons from that.”

“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 guerrillas who 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 U.S. casualties – dead, missing and wounded – went from 7,466 to over 100,000.

McNamara wrote later that he and others had not asked five basic questions: “Was it true that the fall of South Vietnam would trigger the fall of all Southeast Asia? Would that constitute a grave threat to the West’s security? What kind of war – conventional or guerrilla – might develop? Could the U.S. win with its troops fighting alongside the South Vietnamese? Should the U.S. not know the answers to all these questions before deciding whether to commit troops?