Washington ? By mid-afternoon Friday, the familiar clatter of motorcycle engines could be heard caroming off the monuments and memorials across the Mall. They were back, veterans of the Vietnam War, in black leather, streaming into town on their Harleys to gather at the memorial devoted to more than 58,000 of their dead and missing comrades.

Denny Haldeman, 56, a retired Army specialist who spent six months in Vietnam, stood on Constitution Avenue, smoking an unfiltered cigarette after riding 400 miles from his Ohio home. Until 10 years ago, Haldeman said, he never would have come for Rolling Thunder, as today’s motorcycle procession is known, because he was ashamed that he had fought in Vietnam. But seeing so many veterans in the same place at the same time has helped him embrace his past.

“I wasn’t ever proud of what I did over there, but this makes everyone a little prouder,” he said, a few yards from the Vietnam Veterans Memorial, which was crowded with people leaving notes and American flags and tracing the names of the dead etched into the black granite.

‘Pilgrimage’

Started 18 years ago with a couple of thousand participants, Rolling Thunder has evolved into a roaring rite of the Memorial Day weekend in the nation’s capital, a chance for hundreds of thousands of veterans and bikers from across the country to renew old ties, promote veterans’ issues and revel in the adulation of crowds watching the endless procession of leather and metal on wheels.

“It has become a pilgrimage,” said Eric Christiansen, a filmmaker who produced “Homecoming,” a 1999 documentary that chronicled the journey of a group of veterans from California to Rolling Thunder. “After the catharsis at the Wall, they get the pride and joy of being with hundreds of their brothers.”

Compensation

For many of the Vietnam veterans, the crowds are compensation for still-bitter memories of being shunned by large segments of the public when they returned home. Mike “Rattlesnake” Cobb, 58, Rolling Thunder’s chairman, said antiwar protesters spat on him when he flew into Chicago’s O’Hare Airport in 1968. Rolling Thunder, he said, has become “the parade we never had, the recognition we never had.”

Mike Zender, 60, a Marine veteran who served in Vietnam and a retired high school psychology teacher, rode in from Minneapolis Friday for his first trip to Rolling Thunder, hoping to collect memories to replace “the bad ones.” He headed straight for the memorial.

“This is about seeing a lot of guys who were there, shaking hands and seeing who tells the biggest lies,” he chuckled, in a black T-shirt that read, “Nine out of Ten Voices in My Head Say … Squeeze the Trigger.”

Attracting detractors

Taking its name from President Johnson’s “Rolling Thunder” bombing campaign during Vietnam, the procession starts at the Pentagon, crosses the Memorial Bridge and travels along Constitution and Independence avenues. It is not without detractors, who contend that it has turned into an oversized biker party. Bill Line, a spokesman for the National Park Service, which issues the permit for the event, said people have complained about the traffic tie-ups and the noise, though he said most Washingtonians have grown accustomed to it.

One native who will stay away is Robert Dorr, an Air Force veteran who lives in Oakton, Va., and who has criticized the gathering in a column for Air Force Times as a “well-intentioned” but “inappropriate” salute to veterans.

“I don’t want thousands and thousands of motorcycles cluttering up my beautiful city,” he said in a phone interview. “It’s the annual eyesore, as well as an ear-sore. Every year I find myself surrounded by these people on motorcycles.”

‘Touching run

Told of Dorr’s remarks, Artie Muller, Rolling Thunder’s president, said it was a relatively minor inconvenience to endure for a single day. “Most of those guys on motorcycles are veterans who fought in past wars, and if it wasn’t for them, he would not have the town he has to live in so freely and the lifestyle to go anywhere he wants,” Muller said.

Muller compared the noise generated by the mass of motorcycles to a B-52 bombing campaign. “It’s very inspiring,” he said. “It’s a feeling of being there all together, all different veterans from all different wars. It’s a very touching run. There’s not many dry eyes in the crowd.”