What strikes Howard Lambert most is how casual the reference was, written in a Confederate soldier’s diary, between bland notes on his unit’s movements and on finding abandoned enemy provisions.

“We captured three Negro soldiers, the first we had seen,” Private Byrd Willis wrote on May 8, 1864. “They were taken out on the road side and shot and their bodies left there.”

Coming across these lines a century and a half later was “a chilling experience,” Lambert said in a phone interview. “It was like a common occurrence. No ceremony, just, ‘Oh, we lined ’em up and shot ’em.’ ”

On Saturday, the three unknown soldiers of the U.S. Colored Troops will be honored in Culpeper County, Va., not far from where they were executed. It’s part of a years-long effort by Lambert, the head of the nonprofit Freedom Foundation, to highlight the area’s Black history, working together with Civil War Trails and the Piedmont Environmental Council.

Saturday’s ceremony will unveil the Maddensville Historic Site on Madden’s Tavern Road, which includes a granite obelisk commemorating the three men and three historical markers from Civil War Trails explaining other aspects of the area’s history.

Lambert, a native of Culpeper County, has been fascinated for decades by the U.S. Colored Troops, the U.S. Army regiments in the Civil War recruited among free and newly freed Black men. He has researched their history, participating in living history events as a reenactor and even appearing as an extra in movies like “Glory” and “Lincoln.” A semiretired defense contractor, Lambert now spends much of his time back in his home county sharing his research.

At least 160 battles during the Civil War were fought in Culpeper County, according to the local tourism bureau. And though the county, as part of Virginia, sided with the Confederacy, more than a hundred Black men born there went on to serve in the U.S. Colored Troops, Lambert said.

“These men who left, they didn’t have to come back,” he said. “They could have stayed at Freedman’s Village and enjoyed their freedom. But they felt the need to free the rest of [the enslaved].”