ST. LOUIS (AP) — They fought for a country that refused to recognize them as citizens and died in virtual anonymity, their remains lumped together in a single burial plot.

For nearly 150 years, the freed slaves of the 56th United States Colored Infantry who fought for the Union Army in the Civil War were a historical footnote, buried in a mass grave after cholera killed the troops as they prepared to go home.

Even after the remains of more than 100 veterans were relocated to Jefferson Barracks National Cemetery near St. Louis in 1939, they were buried as unknown soldiers.

But, on Monday, a small group of local historians braved a late-morning Memorial Day downpour in a bid to reclaim the memory of the individual men in the 56th Regiment.

Members of the St. Louis African American History and Genealogy Society recited each of the 173 names at a graveside ceremony – after a local veteran uncovered the soldiers’ identities with some cursory research at a St. Louis County library.

A bronze grave marker with those names will be added to a roughly six-foot-tall obelisk marking the 56th Regiment’s burial site later this summer. Two adjacent headstones that refer to unknown soldiers will be removed at the cemetery which is the final burial place for more than 180,000 soldiers dating to 1826, including hundreds of other mass graves and thousands of unknown soldiers.

The grave marker will include the names of 55 soldiers whose remains could not be recovered but were believed to be buried on the banks of the Mississippi River on an outpost once known as Quarantine Island for its role in preventing the spread of diseases. Like other units at the time, the regiment was led by white officers.

Historians with the U.S. Department of Veterans Affairs’ National Cemetery Administration helped verify the authenticity of the 56th Regiment military records.

Though formed in St. Louis in 1863, the 56th Regiment was initially known as the 3rd Arkansas Infantry Regiment (African Descent). Troops were stationed in Helena, a river town in eastern Arkansas, primarily working in logistical support units that guarded railroad bridges and loaded supplies.

In July 1864, they withstood a Confederate attack at Wallace’s Ferry in which their commander was killed. The cholera outbreak occurred as the soldiers prepared to return home by ship in the summer of 1866.

“Today we celebrate the lives, courage and commitment of the men of the 56th,” Cato said in the brief ceremony. “As we read their names, let them know Lord that they are not forgotten.”