William P. Lawrence, a retired Navy vice admiral who was among the highest-ranking members of the armed forces held as a prisoner of war in Vietnam and who later served three years as superintendent of the U.S. Naval Academy in Annapolis, died December 2 at his home in Crownsville, Md. He had a stroke a decade ago. He was 75.

Early on, Lawrence was a test pilot and the first naval aviator to fly twice the conventionally measured speed of sound – 1,300 mph. In the late 1950s, he was a Navy nominee for Project Mercury, which would lift John Glenn and Alan Shepard to orbit and fame as the first Americans in space. Lawrence was disqualified when a minor heart murmur was discovered.

During the Vietnam War, he was commanding officer of Fighter Squadron 143 when he was shot down in North Vietnam in June 1967 and held as a prisoner of war until March 1973. Among others in the prison were John McCain, who went on to become a U.S. senator from Arizona, and future Vice Admiral James Stockdale.

Lawrence once described one of his torturers at Hoa Lo Prison, nicknamed the Hanoi Hilton: “A professional jail er before the war, old Strap and Bar, also known as Pig Eye, soon went to work on me. The flesh was literally stripped from my ankles from writhing in the irons. I still carry the cigarette burns on my arms which are the result of a torture session.”

At other moments, Lawrence said he and other captives crafted playing cards from toilet tissue. They whispered to one another about their favorite hobbies, from European languages to Civil War history – Lawrence’s specialty. He kept his mind sharp by trying to recall names of grade-school friends, thinking up and solving math problems, and writing poetry in his head.

As he later joked: “Sir Walter Scott had genius. But I got time.”

One piece of verse he created while in isolation became, after his release, the official poem of his home state, Tennessee.

Lawrence was among the 591 Americans released as part of “Operation Homecoming.” Shortly after arriving on American soil, he learned that his wife had left him for the Episcopal priest who had comforted her during his absence. He soon remarried, to a physical therapist then helping Mr. McCain.

Lawrence received several top Pentagon appointments. He also served as Naval Academy superintendent from 1978 to 1981, a time when his daughter Wendy graduated from the institution. Wendy Lawrence became a NASA astronaut and mission specialist.

He later said that seeing his daughter go into space – once his dream – “compensates a lot for the difficult things I’ve faced in my life.”

William Porter Lawrence was born January 13, 1930, in Nashville.

Lawrence played three varsity sports at the Naval Academy, was president of the Class of 1951 and ranked eighth academically in a class of 725.

In Vietnam, he was part of a mission to unload cluster bombs on Nam Dinh, lost control of his plane and, bailing at 1,800 feet, landed in a rice paddy.

Two weeks before his death, he completed a memoir, “Tennessee Patriot,” scheduled for publication next fall by the Naval Institute Press.

His decorations included four awards of the Distinguished Service Medal, three awards of the Silver Star, the Legion of Merit, the Distinguished Flying Cross, the Bronze Star with Combat V and two awards of the Purple Heart.