Townsend Walter Hoopes II, 82, a former undersecretary of the Air Force during the 1960s who wrote one of the first accounts of President Lyndon B. Johnson's decision to de-escalate the war in Vietnam, died Sept. 20 of complications of melanoma at the Santa Monica Health Institute in Baja California, Mexico. He lived in Chestertown, Md.
Mr. Hoopes had served as a senior adviser in the Defense Department before becoming Air Force undersecretary. As a civilian on the periphery of power, he became convinced of the impossibility of winning the war after the 1968 Tet Offensive by the North Vietnamese.
The Viet Cong's massive assault against the U.S. Embassy compound in Saigon and other allied targets in January 1968 shocked the American public, which witnessed a U.S. war on television for the first time.
Mr. Hoopes wrote in his 1969 book, "The Limits of Intervention": "This event destroyed most remaining illusions about what a campaign of firepower from the air and 'search and destroy' missions on the ground might accomplish."
His book offered an insider's view of the decision-making process of Secretary of Defense Clark M. Clifford and others after the Tet Offensive and the prevailing perspective that continued escalation was futile.
Mr. Hoopes described his book, which received both acclaim and criticism, as "first a memoir and then, perhaps, history."
"The events in question are still too recent and their consequences still too largely unknown to form a basis for anything resembling a definitive history," he said in response to his critics.
Years later in a Washington Post article, Hoopes wrote: "It is now widely acknowledged that the Tet Offensive was not the shattering military defeat for the U.S. and South Vietnamese forces it appeared to both Washington and the American people."
After his government service, Mr. Hoopes became a fellow at the Woodrow Wilson International Center for Scholars for two years while he researched and wrote his second book, "The Devil and John Foster Dulles" (1973), which won a Bancroft Prize.
From 1973 to 1986, he was president of the Association of American Publishers during a time of dramatic change in the book-publishing industry. He was co-chairman of Americans for SALT, director of the American Committee on U.S.-Soviet Relations and a distinguished international executive at the University of Maryland. When he moved to Chestertown in 2002, he became a senior fellow of Washington College.
Mr. Hoopes, who was known as Tim, was born in Duluth, Minn. He graduated in 1944 from Yale University, where he was captain of the football team and a member of Skull and Bones. He served as a Marine officer in the Pacific during World War II.
After the service, he was assistant to the chairman of the House Armed Services Committee from 1947 to 1948.
For the next 11 years, he worked in the private sector, including seven years at the international consulting firm of Cresap, McCormick and Paget, where he was a partner.
In 1964, he returned to government as deputy assistant secretary of defense for international affairs. From 1965 to 1967, he was principle deputy for international security affairs at the Pentagon.
Mr. Hoopes was a prolific writer of articles and books. His other works included "Eye Power" (1979), written with his wife, Ann; "Driven Patriot: The Life and Times of James Forrestal" (1992), written with Douglas Brinkley, which won the 1992 Theodore and Franklin D. Roosevelt Naval History Prize; "FDR and the Creation of the U.N." (1997), written with Brinkley; and a novel, "A Textured Web" (2002).
In the mid-1980s to 1995, Mr. Hoopes and his wife ran the Hoopes Troupe, an amateur singing group that performed in venues around the Washington area, including the Supreme Court. They donated the profits to charity.
His marriage to Marion Schmidt Hoopes ended in divorce.
Survivors include his wife of 40 years, Ann Merrifield Hoopes of Chestertown; a daughter from his second marriage, Andrea Hoopes DeGirolamo of Rockville; two sons from his first marriage, Townsend Walter Hoopes III of Amelia Island, Fla., and Peter Schmidt Hoopes of Denver; four stepchildren, Lise Jeantet of Berkeley, Calif., Cecily Hoopes Lyons of Washington, Briggs Swift Cunningham IV of Washington and F. Thomas B.C. Hoopes of Ipswich, Mass.; and 11 grandchildren.