At the Battle of Chaffin's Farm, on September 29, 1864, Barnes' regiment was among a division of black troops assigned to attack the center of the Confederate defenses at New Market Heights. The defenses consisted of two lines of abatis and one line of palisades manned by Brigadier General John Gregg's Texas Brigade. The attack was met with intense Confederate fire; over fifty percent of the black troops were killed, captured, or wounded. Barnes was awarded the Medal of Honor for being "[a]mong the first to enter the enemy's works; although wounded." His medal was issued six months after the battle, on April 6, 1865, and he was promoted to Sergeant another three months later, on July 1, 1865.
He remained in the Army after the war, traveling to Texas with his regiment. He died of tuberculosis at an Army hospital in Indianola on December 24, 1866 and buried there in the town cemetery, but his grave, as well as many others, was destroyed by a series of storms that ended up destroying the town. A marker in his memory was placed in San Antonio National Cemetery, San Antonio, Texas.
Among the first to enter the enemy's works; although wounded.
29° 25.276, -098° 28.022
San Antonio National Cemetery