If you traveled on one of the nation's Interstates in these last few days before Memorial

Day, you might have encountered an unusual sight; bikers by the dozens stretched half a mile down the highway, their motorcycles flying military banners and spewing exhaust.

They are an intimidating bunch. Sheathed in leather from the neck down, they look like physical extensions of their bikes. But these riders are no motley crew. They are members of Rolling Thunder, a nationwide network of veterans and their supporters. Their destination: the Rolling Thunder Memorial Day rally on the National Mall in Washington.

Rolling Thunder, which has thousands of members, was founded in 1987 when some Vietnam veterans and advocates for P. O. W. 's and M. I. A. 's befriended one another on the mall. They were looking for a special way to promote their cause. Ray Manzo of Hoboken, N. J. , now a former marine, suggested motorcycles. The idea grabbed them. Masses of bikes descending on Washington would literally sound like Rolling Thunder, the code name for the bombing campaign over North Vietnam.

In its first year, the Memorial Day rally drew 2,500 bikers. Now, nearly two decades later, hundreds of thousands of bikes join in.

"When you put 200,000 bikes together," said Michael DePaulo, a Vietnam veteran from Berkley, Mass. who helps organize and run the rally, "it sounds like a B-52 strike."

One rider is Steve Britton, a former marine from Dillon, Colo. With his leather vest, cowboy boots and grizzled mutton chops, he resembles a sheriff in a western county. And like many of his comrades, Mr. Britton is very much a modern cowboy. "I love the freedom and the air and the bugs in my teeth," he said of his attraction to motorcycles.

Riding also renews Mr. Britton's sense of self-worth, which he said he lost after he received hostile and indifferent receptions upon returning from Vietnam in the late 1960s. he said post-traumatic stress disorder and alcoholism prevented him from holding a steady job. "I was at the point where I was saying, 'God, either kill me or cure me,' and I really didn't care which."

But Mr. Britton turned to Christianity, joined the Christian Motorcyclists Association and found salvation on the open road. He carries a small Bible on his annual ride to Washington. The art on the cover depicts handlebars and shining headlights. The caption reads: "To for the Highway."

He serves as a chaplain for Rolling Thunder bikers. "That's why I go on the ride," he said. "To be able to share with people, to pray with people."

Mr. Britton pilots a bright purple Honda Gold Wing. His bike is equipped with plush purple seats and velour arm rests. He fills his five-CD changer with Randy Travis recording and keeps a pouch of Twizzlers on the dash to tame his cigarette addiction. At gas stations, he drinks cups of black coffee; even at 65 miles an hour, the bike can lull a rider to sleep.

Mr. Britton is one of 50 or so Rolling Thunder bikers who meet in California and ride their motorcycles to Washington each spring. They call themselves Carry the Flame, and they take an Olympic-style. "torch of remembrance" to soldiers' families who are unable to visit the Vietnam Veterans Memorial. The bikers stop at Harley-Davidson outfitters and V.F.W. posts to conduct flame-lighting ceremonies.

Most of the Carry the Flame riders are veterans who say they see the 10-day, eight-state, 3,000-mile journey as a powerful expression of identity and pride and a way to cope with the past,

"The ghosts get let out of the box," said King Cavalier II, a founder of Carry the Flame. He said that during the ride from California to Washington "full-grown 250-pound men break down like babies" because the experience makes them confront memories and emotions that have "been repressed for 30 years."

Mr. Cavalier grows somber and becomes teary-eyed when he stops

A．it was a nationwide network of veterans and their supporters founded in 1987 that affiliated to Rolling Thunder National.

B．It was an organization founded in 1995 that works year-round for veterans' fights.

C．It was named Rolling Thunder because masses of bikes descending on Washington would literally sound like Rolling Thunder.

D．It was named Rolling Thunder because it was the code name for the bombing campaign over North Vietnam during the Vietnam war.