Most Friday evenings, the rat-a-tat-tat of drums and the trill of fifes float faintly over the streets of downtown Leesburg. Inside the hall of a small red-brick church, young people gather each week to recreate a military tradition.

Matt Buttery, 17, has been coming here for seven years to play with the Loudoun Border Guards Fife & Drum Corps. Buttery bought his first fife for $5 during a fourth-grade field trip to George Washington's Mount Vernon estate and has been fascinated by the tiny instrument and its place in history ever since.

"It's hard to put into words," said Buttery, who plays football and sings in the chorus at Heritage High School. "I really like the songs, to begin with, and to play them feels really good."

Buttery and the 20-odd other members of the Loudoun Border Guards, one of only a few youth fife and drum corps in the Washington area, perform year-round at such events as Loudoun's Court Days in August. They also have traveled to New York and Florida to play. But early July is among the busiest times for the group, as communities turn to the young musicians to provide patriotic tunes for Fourth of July celebrations.

The Border Guards are scheduled to head to Warrenton this afternoon for a children's parade and then back to Leesburg to entertain guests at a fireworks display in Ida Lee Park. And that's after two scheduled parades and a performance in Reston earlier in the week.

Anne Quinn, a longtime fifer, and her husband, Cormac Quinn, a drummer, founded the Border Guards in 1996. For most performances, the musicians don black pants, gray coats and red sashes, uniforms modeled after those worn by the Hillsboro Border Guards, a pre-Civil War militia group from the Loudoun County town of Hillsboro.

The modern Border Guards were started through a partnership with the Loudoun Museum, but the group broke off last year and became a separate nonprofit organization, Anne Quinn said. In 2002, the group produced its first CD, a compilation of Christmas music and patriotic songs.

Tim Sutphin, musical director for the Colonial Williamsburg Fifes and Drums, said the first known pairing of fifes and drums was by the Swiss in the 14th century. In the United States, the musicians marched in the Revolutionary War and the Civil War, with the drumbeats helping soldiers keep a steady pace and the music alerting soldiers when it was time to wake up, stop to eat and even gather wood.

"This is the music that our ancestors heard, and these kids are bringing it alive," Sutphin said.

Though the fifers and drummers -- ranging in age from 10 to 18 -- said they appreciate the history, they're also in it for the fun. They travel across the country to perform at musters, gatherings of fife and drum corps that always involve camping and jam sessions and usually involve silly string and water balloons.

"When you join, there's an entire world that nobody knows about unless you're part of a fife and drum corps," said Krista Letson, 18, who just graduated from Loudoun County High School.

Ashley Anderson, 18, a student at Virginia Commonwealth University who's been a corps drummer for about 21/2 years, said some of her friends "think we're weird." But those friends, she said, "just don't get fife and drum."

During a recent practice, Anne Quinn stopped the fifers mid-note as they struggled through a new song, an arrangement of music from the motion picture "Pirates of the Caribbean."

"That was quickly going downhill," she said. "Let's pick it up from the triplets."

A few more tries and the song was coming together. "The only thing it needs now is practice," Quinn told her students. "We could play it now until we're blue in the face."

Quinn, who got hooked on the fife as a child when she listened to a New York corps play during summer vacation, said she still gets goose bumps when she hears "America the Beautiful," "The Star-Spangled Banner" and other standards.

"I cry all the time," Quinn said. "We have a whole show we built around the history of the country and the strife of the American people. . . . I get choked up every time I hear it."

The uniform for the Loudoun Border Guards Fife & Drum Corps is based on that of a 19th-century Loudoun militia.