Official Plan of The Siege Of Yorktown Va. Conducted by the Army of the Potomac under the 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. ... Lith. by J.F. Gedney, Washn. Chas. G. Krebs, Engr.