The ceremony at the grave of Union Pvt. William Christman kicked off a month of activity marking the sesquicentennial of the cemetery, across the Potomac River from the nation's capital.
Christman, a member of the 67th Pennsylvania Infantry, was buried May 13, 1864, after contracting a case of measles. The land was officially designated as a military cemetery a month later.
James Christman of Allentown, Pennsylvania, a great-grandnephew, said he and his cousins had no idea their ancestor had even served in the Civil War, much less that he was the first soldier buried at Arlington. They found out this year when contacted by a local historical association. Christman said he suspects his grandfather knew of the honor, which has been well documented at Arlington, but that he simply never bothered to tell anyone.
"My grandfather was a man of few words," Christman said.
The Christman family continued to have a long history of military service, even as the family's service in the Civil War had been forgotten.
Standing in the rows of graves, great-grandniece Barbara Christman Page of Swiftwater, Pennsylvania, thought about how her great-granduncle was the first of 400,000 from the nation's wars to be buried at Arlington.
"It is just so overwhelming," she said.
Arlington Cemetery sits on land that had been the home of Confederate Gen. Robert E. Lee. The Union army occupied the estate after Virginia seceded from the Union and turned it into a burial ground in part as a way to spite Lee.