Following his discharge, Sheehan spent two years covering the war in
Vietnam as UPI's
Saigon bureau chief. In 1963, during the
Buddhist crisis, Sheehan and
David Halberstam debunked the claim by the
Ngô Đình Diệm regime that the
Army of the Republic of Vietnam regular forces had perpetrated the
Xá Lợi Pagoda raids, which U.S. authorities initially accepted. They showed instead that the raiders were
Special Forces loyal to Diệm's brother,
Nhu out to frame the army generals. In 1964, he joined
The New York Times and worked the city desk for a while before returning to the
Far East, first to
Indonesia and then to spend another year in Vietnam. Sheehan was one of numerous U.S. and international journalists who received valuable information from
Pham Xuan An, a 20-year veteran correspondent for
Time Magazine and
Reuters, later revealed to also be a spy for the
National Liberation Front for South Vietnam. In the fall of 1966, he became the
Pentagon correspondent. Two years later, he began reporting on the
White House. He was a correspondent on political, diplomatic, and military affairs. After being notified of their existence by
Marcus Raskin and Ralph Stavins at the
Institute for Policy Studies, Sheehan copied the
Pentagon Papers for the
Times on March 2, 1971, against leaker and Vietnam-era acquaintance
Daniel Ellsberg's wishes. He made the copies with the help of his wife Susan in numerous copy shops in Boston, then they flew with the copies to a hotel room at
The Jefferson in Washington for reading, before mailing them to his editor
James L. Greenfield's apartment, then he worked with Greenfield and a large team of editors, writers and lawyers on organizing the copies for publication in the
New York Hilton Midtown, as he would later reveal in 2015. Sheehan published an article in the
New York Times Book Review on March 28, 1971, entitled "Should We have War Crime Trials?". He suggested that the conduct of the Vietnam War could be a
crime against humanity and that senior U.S. political and military leaders could be subject to trial. In response, the Pentagon prepared a detailed rebuttal justifying its conduct of the war and exonerating senior commanders, however, the rebuttal was never released due to the belief that it would only exacerbate the issue. Sheehan published his first book,
The Arnheiter Affair, in 1972.
Marcus Aurelius Arnheiter, the subject of the book, proceeded to bring an action for
libel against Sheehan but was ultimately unsuccessful. The time and effort spent fighting three libel suits in connection with his first book that endured until 1979, and Sheehan's lengthy recovery from his injuries, delayed work on his Vietnam book. After the
Times ended his unpaid leave in 1976, he formally resigned from the newspaper to continue work on the book. Although he received an advance of $67,500 (of which he was entitled to $45,000 prior to publication) from
Random House in 1972, Sheehan – a "dreadfully slow" writer who "[chased after] the last fact" – mainly subsisted on lecture fees and fellowships from the
John Simon Guggenheim Memorial Foundation (1973–1974), the Adlai Stevenson Institute of International Studies at the
University of Chicago (1973–1975), the
Lehrman Institute (1975–1976), the
Rockefeller Foundation (1976–1977), and the
Woodrow Wilson International Center for Scholars (1979–1980) for the remainder of the 1970s. According to William Prochnau, the latter fellowship marked a significant "turning point" for the book, as Sheehan "talked about Vietnam all day long every day" with
Peter Braestrup after abandoning several hundred manuscript pages later characterized as a "false start" by Susan Sheehan. When Sheehan finished "three-fifths of the manuscript" in the summer of 1981, the initial advance was renegotiated and raised to $200,000 with a projected delivery date of 1983, while
William Shawn of
The New Yorker agreed to excerpt the finished manuscript and advance funds as needed. It also won the
National Book Award for Nonfiction. In 1990, Sheehan received the Golden Plate Award of the
American Academy of Achievement. ==Later life==