PASCAGOULA (AP) — Former presidential candidate Ross Perot joined more than a thousand other people Saturday as the U.S. Navy christened a new destroyer named for an admiral who spent six years in captivity in North Vietnam before resuming a career that included a stint as head of the Naval Academy.

The $1 billion William P. Lawrence, being built at the Northrop Grumman Corp. shipyard at Pascagoula, is the 60th of the Arleigh Burke-class of destroyers and the 28th built by Northrop Grumman. They are among the largest and most powerful destroyers ever built.

Perot, who was a junior classman to Lawrence at the Naval Academy and later — like Lawrence — served as class president and battalion commander, called his mentor a ‘‘true American hero’’ who became one of the most widely beloved officers in Navy history — while never allowing his rank and fame to affect him.

‘‘He is kind and gentle, but he is tougher than steel,’’ Perot said, referring constantly in his tribute to Lawrence in the present tense. Lawrence died in 2005 at the age of 75.

Lawrence, a native of Nashville, Tenn., graduated in 1951 from the Naval Academy. He became a combat pilot and was the first Navy aviator to fly at twice the speed of sound. He almost became an astronaut — Perot said a minor condition kept him from those ranks — and then flew in Vietnam where he was shot down on June 28, 1967 after completing a mission.

In a POW camp, Lawrence battled his captors for better conditions and worked to keep up the morale of his fellow prisoners with the command ‘‘never give in’’, Perot said. To keep his own spirits up, Lawrence wrote a poem ‘‘Oh Tennessee, My Tennessee,’’ that became that state’s official poem after his release in 1973.

The motto of the new warship is ‘‘Never Give In.’’

Lawrence continued with a military and career that include a Pacific fleet command and superintendent of Annapolis. One of his two daughters, now-retired Navy Capt. Wendy Lawrence, flew on four space shuttle missions as an astronaut.

‘‘That’s pretty good for a guy who was in hell for all those years,’’ said Perot, who worked during the Vietnam War to obtain better treatment for U.S. prisoners.

Rear Adm. William E. Landay III called Lawrence ‘‘a man of uncommon valor and decency.’’

‘‘By naming this ship in honor of William P. Lawrence, we are reminded that freedom is not free,’’ Landay said. ‘‘It comes at a terrible price.’’

Lawrence’s widow and the ship’s sponsor, Diane Wilcox Lawrence, of Annapolis, Md., called her husband ‘‘a very modest and humble man.’’

‘‘If he were here now, he’d ask what all the fuss was about,’’ she said.

After the christening, Lawrence’s radar interceptor on the F-4B Phantom that took both into the hands of the North Vietnamese, agreed.

‘‘He had no airs,’’ James William Bailey, 67, of Anderson, S.C. ‘‘He was represented and beloved by all the men.’’

Diane Lawrence and Lawrence’s daughters, Wendy Lawrence and Dr. Laurie Macpherson Lawrence, broke three bottles of champagne on the ship’s bow to officially give it its name. It officially will become the USS William P. Lawrence after it is turned over to the Navy late this year.

The 9,200-ton destroyer is 509 feet in length and will have a crew of 276.