Samuel Williams was born into slavery around 1827 in Albemarle County, Virginia. By the early 1860s, his owner was John Brice, who lived in Pike County, Missouri. Williams enlisted in the Union army on February 20, 1864, in Louisiana, Missouri, for a period of three years. He mustered in as a private in Company D of the 4th Missouri Colored Infantry Regiment at Benton Barracks in St. Louis, Missouri, on March 10, and the following day, the army renamed the unit the 68th USCT Infantry Regiment. 

The 68th USCT took part in numerous operations throughout the South. The men were stationed in St. Louis until April 27, 1864, when they moved to Memphis, Tennessee. They remained there until February 1865 and then took part in the Battle of Fort Blakely in April 1865. The battle was an overwhelming Union victory, in large part because of the efforts of African American troops like Williams. After the battle, the regiment was stationed in Montgomery and Mobile, Alabama, until June. The men were briefly stationed in New Orleans before moving to Texas. They mustered out at Camp Parapet, Louisiana, on February 5, 1866, and Williams then disappeared from the historical record.