I have limited information on the Army of the Potomac in that time period. A soldier of the 97th New York said there were only two Blacks in his regiment, both employed as cooks. Another soldier saw several armed Black troops in the 18th Pennsylvania Cavalry. Even using a rough estimate of only four Blacks per regiment or battery, the total would approach a thousand, working on or near the front lines. But the logistics/supply services undoubtedly employed significantly higher percentages.