In August 1863, as part of his duties as aide-de-camp to General Barnard, Alexander was named as a member of a board of military officers who would examine the defenses of Washington and suggest improvements as needed. The board, created by the Secretary of War, Edwin M. Stanton, was designed to replace a civilian board that he had created in 1862. In a November 1863 meeting, this board recommended final allotments of guns and ammunition for the forts protecting Washington, D.C., thus establishing the number of guns that would be in place during the Battle of Fort Stevens eight months later.