Conducted by the Army of the Potomac under command of Maj. Gen. George B. McClellan, U.S.A., April 5th to May 3rd 1862 Prepared under the direction of Brig. Gen. J. G. Barnard, Chief Engr., by Lieut. Henry L. Abbot, Top. Engrs. A.D.C. Chas. G. Krebs, Engr