 Tidball commanded the artillery of the II Corps of the Army of the Potomac during the Overland Campaign, including the Battle of the Wilderness, April 1864–July 6, 1864.He was commandant of cadets at West Point from July 10, 1864 to September 22, 1864.He then returned to the field, leading the artillery of the IX Corps from October 8, 1864 until April 24, 1865 in the Appomattox Campaign and April 24, 1865–June 30, 1865 in the Department of Washington.