That was Colonel Edwin Vose Sumner
Edwin Vose Sumner was a United States Army officer who became a Union Army general. He was the oldest field commander of any Army Corps on either side during the American Civil War. He led the second Corps of the Army of the Potomac through the Peninsula Campaign, the Seven Days Battles, the Maryland Campaign, and the Right Grand Division of the Army during the Battle of Fredericksburg. Sumner fought in the Black Hawk War, with distinction in the Mexican–American War, on the Western frontier, and in the Eastern Theater for the first half of the Civil War.