From the position of the batteries of the enemy which flanked the mine work, it was evident that there would be great difficulty in bringing a direct fire of sufficient power to silence them so promptly as to protect our assaulting columns. The redoubt is well placed, in a commanding position, and well provided with traverses. It was, therefore, considered as indispensable that we should bring, in addition to the horizontal,a powerful vertical fire to bear upon the redoubt and sunken batteries near it. All the siege mortars remaining in the train (viz, ten 10-inch and six 8-inch) were, therefore, set apart for this service. The Coehorns were distributed along the line, so that all points of the enemy's position should be more or less under a vertical fire. The location of the different batteries will be seen by a reference to the drawing submitted herewith.* They were constructed by details from the different corps under the general direction of Major Duane, chief engineer.

On June 30 Brooker's battery (B), First Connecticut, six 4 1/2-inch siege guns, was placed in Battery No. 19, which commands the enemy's crest, behind the mine.

July 6, for 8-inch mortars were placed in Battery No. 29. They were served by a platoon of Battery A, First Connecticut, Captain Gillett.

July 8, two 8-inch mortars and July 9 four Coehorns were placed in battery near the Hare house, under command of Lieutenant Sargeant, Battery G.

July 14, the Fourth New York Artillery, Lieutenant-Colonel Allcock commanding, reported for duty with the siege train.

July 25, Pratt's battery (M), First Connecticut, six 4 1/2-inch siege guns, was placed in position in Battery No. 24. A few field batteries were also in position on the line.

July 28, orders were given to prepare for an assault, and on that night ten 10-inch mortars and six 8-inch were placed in position, the 10-inch in Battery No. 8, the 8-inch in Battery No. 9; the first served by Captain Pierce's battery (C), First Connecticut, the latter by part of Battery A, Lieutenant Patterson.

On the night of the 29th Captain Brown's battery (H), First Connecticut,+ six 4 1/2-inch siege guns, Battery No. 4, and the field batteries of the Fifth and Eighteenth Corps, not heretofore on the lines, were placed in position.

On the 28th I visited the different batteries and gave detailed instructions for the employment of each gun under the different probable circumstances that might arise. These orders were impressed on the battery officers by their commanders, and on the morning of the 29th circular instructions were furnished to all artillery commanders (see Appendix H) for their government. The following pieces were placed in battery in front of the Fifth and Ninth Corps: ten 10-inch mortars, ten 8-inch mortars, 17 Coehorn mortars, 18 siege guns, 86 field guns; total, 141; and near the Hare house, to bear upon the enemy's batteries and lines on the right of Burnside's corps, six 8-inch mortars, 11 Coehorns, 6 field guns; total, 23. The total number of guns and mortars was, therefore, 110 guns and 54 mortars.

On the morning of the 30th, as soon as the mine exploded, our fire opened along the whole line. The firing was from each piece slow, deliberate, and careful, partaking of the nature of target practice, and was very effective, the amount of fire required being provided for by the large number of pieces brought into action. The enemy's guns in

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*To appear in the Atlas.

+Brown's battery belonged to the Fourth New York Artillery.

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