Just a few steps from Frog Pond, tourists walk by the monument to the Oneida boys, which was dedicated in 1925 in a ceremony attended by six of the seven surviving team members. The team began play in 1862, in the middle of the Civil War. Today, in the oldest city park in the country — 50 acres filled with majestic bronze statues — few notice the 6-foot, shoulder-width marble tablet that looks like an oversized cemetery headstone.

Its inscription reads: “On this field the Oneida Football Club of Boston, the first organized football club in the United States, played against all comers from 1862 to 1865. The Oneida goal was never crossed.”

The Oneida roster was as much a Massachusetts history lesson as it was a group of young men beating each other up on Boston Common. Carved into the back of the monument is the roster, the 16 original team members. Many are instantly recognizable as key figures in Boston history: captain and Oneida founder Gerrit Smith Miller, Edward Lincoln Arnold, Robert Apthorp Boit, Edward Bowditch, Walter Denison Brooks, George Davis, John Malcolm Forbes, John Power Hall, Robert Means Lawrence, James D’Wolf Lovett, Francis Greenwood Peabody, Winthrop Saltonstall Scudder, Alanson Tucker, Louis Thies, Robert Clifford Watson, and Huntington Frothingham Wolcott.

The names have a place in the long history of football, just the same as Lombardi, Halas, and Thorpe. But of the descendants gathered together by a reporter for a photo at the marker last month, only one knew of the monument and his family’s connection to football. The rest were seeing their place in football history for the first time.

Keeper of the flame The Oneida Football Club hasn’t played in 147 years, yet Tom McGrath has as much enthusiasm for his team as any Patriots season ticket-holder does for his. McGrath, 64, is the self-appointed Oneida team president, a title the Beacon Hill resident takes seriously, and one he has held for almost two decades. He pays a yearly fee of $50 to the city of Boston to keep Oneida a registered organization, with himself as president. McGrath acts as the Oneida guardian, protecting it, as the monument states, “against all comers.”

When a rugby club in Cambridge tried to take the name, McGrath was there to stop it. And when the football carved into the monument top was changed to the current soccer ball shape in the early 1990s, McGrath said, it took him six months to identify who was responsible and convince them to provide $5,000 to reinforce the monument. All of this requires a small budget, and the Oneida Football Club, which ceased to exist after 1865, has a checking account in 2012 at Bank of America.

“It was one of those things, it doesn’t jump out at you as a major tablet to anything,’’ said McGrath of the monument. “I became just interested in the history of the organization — not the sport, I have to make that clear.

“I had no interest in sports. But it had something to do with my interest in historic preservation. I had been walking by that tablet for years and I noticed that there wasn’t a football on it anymore.

“I had always seen a football, just walking across the common and looking at it, and not knowing what the Oneida Football Club was, or cared. And then when I noticed it was not a football anymore, it was a soccer ball, I said, ‘Well, that’s interesting.’ Then I started researching what the Oneida Football Club was.’’

Born in Whitman, McGrath graduated from Cardinal Spellman, where he had some interest in football but never got the chance to play for Peter Ambrose, the Brockton school’s longtime coach and a member of the Massachusetts High School Football Coaches Association Hall of Fame.

“Peter Ambrose wouldn’t let me on any of the teams because I was too skinny,” said McGrath. “I weighed about 120 pounds when I was 18.”