Gardners Photographic Sketch Book Of The War. Vol. 1, No. 14. Mortar Battery No. 4 Near Yorktown, Virginia. May, 1862. This represents one of the batteries planted for the bombardment of Yorktown. In places subjected to mortar fire, the men construct bomb proofs, and place a sentinel on the watch, to give warning of the approach of a shell, and enable every man to seek shelter till the explosion of the missile. If the bombardment is continuous, the troops remain under cover, unless absolutely required to man the works. The mortars of Battery No. 4 were of thirteen inch calibre, and required great labor to place them in position. As the fire of mortars is entirely a work of calculation, it is not necessary for the gunners to see the object against which the shells are directed, and accounts for the position of this Battery under the high bank.
Library of Congress says: Siege of Yorktown, Va. Federal Battery No. 4 mounting ten 13 inch mortars
