be borne in mind that there is a difference in the scale); map 3, plan of external works immediately connected with Yorktown; map 4, general topography and delineation of the enemy's line across the Peninsula. I regret that there is not time and means to prepare a complete plan of this enormous system of defenses. They should form part of the record of the operations of the Army of the Potomac.
The forcing of such a line with so little loss in itself is an exploit less brilliant, perhaps, but more worthy of study, than would have been a murderous assault, even if it had proved successful.
I am, very respectfully, your most obedient,
J. G. BARNARD,
Brigadier General, and Chief Engineer Army of the Potomac.
General JOSEPH G. TOTTEN,
Chief Engineer, &c., Washington, D. C.
Journal of the siege.
Saturday, April 5.-The headquarters of the army reached-Church about 1 o'clock. General Heitzelman joined us; the chief engineer accompanied him to the front and examined the enemy's lines.
Sunday, April 6.-The chief engineer went up to the front with Lieutenant McAlester, and reconnoitered ravines in front of Yorktown and gave general instructions to Lieutenant Merrill to reconnoiter Warwick River to connect with Lieutenant Comstock; to Lieutenant Comstock to reconnoiter from Wynn's Mill down to connect with Lieutenant Merrill; to Lieutenant McAlester to reconnoiter works in front; also to Lieutenant Abbot to survey ravines.
Monday, April 7.-The chief engineer accompanied the commanding general to examine the enemy's position along Warwick River from Southall's Landing down; instructed Lieutenant Comstock to repair to General Keyes' headquarters and continue the various reconnaissances up to Wynn's Mill. Lieutenant Abbot reconnoitered front of Yorktown fort.
Tuesday, April 8.-Engineers employed in the reconnaissances mentioned.
Wednesday, April 9.-Lieutenant Comstock temporarily with General Keyes reconnoitering from Wynn's Mill down to connect with Merrill's reconnaissance; Lieutenant Merrill with Keyes reconnoitering Warwick River from Lee's Mill down; Lieutenant McAlester reconnoitering from left of Yorktown road to Wynn's Mill; Captain Duane and command at Ship Point.
Thursday, April 10.-Engineers employed as before; Captain Duane came in with his command, leaving 10 at Ship Point to look out for engineer property. Lieutenant Abbot obtained very satisfactory reconnaissance of Yorktown lines. The chief engineer selected an engineer and artillery depot in company with the chief of artillery, and examined the road between Cheeseman's Back Creeks. Examined the Yorktown and Gloucester shore and works from Farinholt's house.
Friday, April 11.-Captain Duane and command to move down to the engineer depot and make arrangements for getting up bridge equipage and engineer materials and tools. Lieutenant McAlester was
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