 The commander of the 1st Vermont, John W. Phelps, was soon promoted to brigadier general and command of a brigade, so Washburn was the regiment's "de facto" commander during nearly all of its three months of service at Fortress Monroe and Newport News, Virginia.Washburn also commanded five companies of the 1st Vermont and five from the 4th Massachusetts infantry at the Battle of Big Bethel on June 10, 1861.He was mustered out with his regiment on August 15, 1861.