A part of the United States Colored Troops, the regiment saw action in Virginia during the war and later served on the Texas frontier.
Three members of the 38th, William H. Barnes, James H. Harris, and Edward Ratcliff, were awarded the Medal of Honor for their actions at Chaffin's Farm.
The unit saw duty at various points along the Rio Grande in the southern portion of the state, including Brownsville and Brazos Santiago, as well as at Indianola and Galveston on the gulf coast.
It was organized on 1 October of that year at Jefferson Barracks, Missouri, and was stationed in New Mexico Territory and along the transcontinental railroads then under construction.
The memorial also honors all of the approximately 700 African-American men from St. Mary's County, Maryland, who served in several different regiments and also on sailing ships of war or transport in the Civil War, as well as the 80 or so White St. Mary's County residents who served on the Union side, one of whom was also a medal of honor recipient.