Paisley's retirement was sporadic at best. He frequently cut short sailing trips to go to Washington on what he said was CIA business. One reason Paisley was called back to the CIA was William E. Colby. 'Colby loved him. He really was very fond of him,' Sam Wilson remembers. Wilson says Paisley agreed to me back in and do a few individual jobs for Colby at the quest of John M. Clark, who was then Wilson's deputy. Wilson remembers that the first time he met Paisley, he was prepared to spend half an hour with him, but he was so enthralled with his abilities, he let the meeting go on for two hours. When he was done, Wilson found Paisley to be erudite, sophisticated, cultured, witty.''`Oh, what a sense of humor! He had it all together. Not greedy, not hungry, not ego-stricken ... I liked him,' Sam Wilson stated.

Wilson says Paisley enjoyed his new assignments. He 'seized upon the new challenges with quiet alacrity. He didn't miss a beat - no pause, no hesitation - as though he'd gotten sort of reinfected.'

At a retreat for top CIA officials in Warrenton, Virginia, Sam Wilson got a close look at Paisley. 'I remember him as a very incisive reasoner. It wasn't so much inductive as deductive. I know because we worked problems together some. Some times he would circle a problem and then intuit an answer. I would wonder how he got that. Just a straight line right into the center of the problem. He had a capacity to intuit that I have seen in some women, but I seldom see it in a man. I call it circular logic or a circular pattern of reasoning. You circle something like this, thinking about it, and all of a sudden inspiration hits you and wham-o, you've got it. I can't do it and I don't trust it when I think I am doing it.'

William R. Corson, a retired Marine lieutenant colonel who was an expert on revolution and counterinsurgency and was nearly court-martialed for writing a book venting his disillusionment over the Vietnam War, died on Monday at a hospital in Bethesda, Md. He was 74 and lived in Potomac, Md. The cause was emphysema and lung cancer, his wife, Judith, said.

In early 1968, Colonel Corson was just back from a tour in Vietnam and working in the Defense Department, looking forward to retirement. He spent much of his spare time hunched over a typewriter at home, working on a book he would call "The Betrayal."

Colonel Corson had never believed in the "domino theory" that one Communist takeover would lead to another, and he had long thought that the struggle in Vietnam was more about nationalism than Communism, his wife said.

The publisher, W. W. Norton, planned to publish the book the day after Colonel Corson's retirement became effective. But the colonel ran afoul of a regulation requiring officers to submit statements on public policy for official review before making them public.

Unconvinced by his argument that the regulation should not apply to him because he would be a civilian when the book came out and that his manuscript violated no national-security laws in any event, the Marine Corps delayed his retirement and moved to convene a court-martial. As the debate grew heated, the corps dropped the court-martial, and Colonel Corson retired a month later than planned.

The book condemned the assumptions that had led the United States into a quagmire. "The politicians saw in Vietnam, or so they thought at the time, a chance to pull off a cheap victory against the Communists," he wrote. "When their initial judgments about Vietnam were found to be in error, there was no way to confess their error, without risking defeat at the polls."

Colonel Corson argued that the American-backed Saigon government was inept and corrupt and out of touch with the people.

William Corson became familiar with Southeast Asia as a young officer. After service in the Korean War, he learned Chinese at the Naval Intelligence School in Washington. In the late 1950's he was stationed in Hong Kong, and in 1962 he was assigned to the office of the secretary of defense. From 1964 to 1966, he taught a course on communism and revolution at the Naval Academy.

In 1966, he was sent to command a tank battalion in Vietnam, a country he had been studying since it was a French colony. In 1967, he was named head of the Combined Action Program, in which marines aided South Vietnamese militia in villages. Colonel Corson's superiors praised his ability to win the confidence of the Vietnamese. Had he decided to remain in the corps instead of retiring, he seemed destined to wear the eagle of a full colonel, perhaps even the star of a brigadier general.

His career path had been unusual. Born in Chicago, he spent much of his early childhood with his grandparents after his mother and father divorced. As a teenager, he preferred wandering and odd jobs over the classroom. Then he got a job at The Chicago Daily News, whose publisher saw something in him.

The publisher was Frank Knox, later to become secretary of the Navy, who was on the board of the University of Chicago and helped the young man get a scholarship to the university.

William Corson enlisted in the Marine Corps in World War II and fought in Guam and Bougainville in the Pacific, rising to sergeant. After the war, he returned to the University of Chicago and earned a degree in mathematics. He received a master's degree in economics at the University of Miami and re-entered the Marines in 1949 as an officer. Years later, he got a doctorate in economics from American University in Washington.

After leaving the Marines, he taught history at Howard University in Washington for a year and wrote several books on national-security issues. He also was compliance director of the Price Commission, the agency created in 1971 as part of President Richard M. Nixon's efforts to stabilize the economy and hold down inflation.

In addition to his wife, Colonel Corson is survived by their three sons, Adam, Zachary and Andrew, all of Potomac; two sons from an earlier marriage, Christopher, of Silver Spring, Md., and David, of Greenville, S.C.; and five grandchildren.

Despite the unpleasantness surrounding his retirement, Colonel Corson remained a marine at heart, up to a point. "I could kill you in eight seconds," he boasted to an interviewer a year after leaving the corps. "But I don't have the instinct for that sort of thing anymore."