William Albert Tidwell, 81, a retired Army Reserve brigadier general and intelligence officer who wrote books about the assassination of President Abraham Lincoln, died of cancer June 16 at his home in Fairfax.

He served on active duty with the Army in Uruguay during World War II and in Vietnam, where he was chief of reconnaissance and photo intelligence in the mid-1960s. He worked at the Central Intelligence Agency in the 1950s and 1960s.

At the CIA, he helped identify Soviet missiles in Cuba in the early 1960s and was special assistant to the deputy director of intelligence. He retired in 1969 as chairman of the CIA committee on imagery requirements and exploitation, overseer of the U-2 spy plane program.

After he retired at the CIA, he was a senior systems analyst with Mitre Corp. until 1993, working on defense issues.

He was co-author with James O. Hall and Dave Gaddy of "Come Retribution," a 1988 book that detailed Confederate plans to kidnap and assassinate Lincoln. The Washington Post's review of the book said its outline of Confederate intelligence activities and clandestine secret service operations was "by far the best such account in print."

"Come Retribution" won an award from the National Intelligence Study Center as the best book on intelligence written that year. He also was the author of another book on Lincoln, "April 65."

He was born in Hillsboro, Tex., and raised in Indianapolis. He was a graduate of the Virginia Military Institute.

From 1975 to 1993, he operated a vineyard in Rollins Fork, Va.

His honors included a Legion of Merit.

He was a member of the Cosmos Club and the American Legion.

Survivors include his wife, Virginia Tidwell of Fairfax; five children, Claudia Tidwell of Silver Spring, Cynthia Chillem of Cleveland, Patricia Tidwell of New York, John Tidwell of Fairfax and Alan Tidwell of Sydney; and nine grandchildren. A son, Robert Tidwell, died in 1993.