road toward the Blackwater Swamp. Lieutenant Lydecker accompanied me during the reconnaissance, and was subsequently directed to trance the line and place in position the troops ordered to hold it. The site for a new redoubt was chosen between the Norfolk railroad and the swamp, and its construction placed under the direction of Captain Harwood, who had been relieved from duty with the Ninth Corps the same day.

On the 12th the camp of general headquarters was moved from Jones' to a more central position near Burchett's and in rear of the center of the Ninth Corps.

On the 14th orders were issued to have the old works of the enemy demolished. This had been his advanced position, and the first to be taken by assault. The redoubts and batteries, in fact the whole intrenched line, had been beautifully planned and constructed at a much earlier period, in view of the probability of a demonstration being made against Petersburg. The site selected was a most magnificent and commanding one, the natural lay of the open fields in front forming a most perfect glaces. Fortunately surveys were made of this line, and maps of the works preserved, a set of which will be appended.

Toward the close of the month everything was in readiness to explode the mine which had been in course of construction in front of the Ninth Corps. In company with Colonel Spaulding and Lieutenant Benyaurd I had the great gratification of penetrating the gallery and its lateral branches, and of examining in detail its construction, the mode of ventilation, and the arrangement of the chambers. Lieutenant-Colonel Pleasants, who kindly offered to accompany the party and explain the nature of his labors, and to whom all are highly indebted for his politeness, had prepared a highly interesting report, giving a succinct account of the manner of driving the gallery and its lateral branches, the nature of the soil encountered, the construction and dimensions of the chambers, the charging and tamping, with other interesting facts connected with the history of the mine from its first inception to its completion. Accurate drawings have also been prepared by him to accompany the report. From it I extract the length of the main gallery to be 510.8 feet and each of the lateral galleries 37.5 feet; radius of crater, 25 feet; work commenced June 25 and finished July 23.

The different engineering operations, which had been pushed forward night and day, were fast progressing toward completion. The several batteries, constructed with the utmost care and in the highest order of professional skill, had received their armaments of guns and mortars, and only waited the moment to play a conspicuous part in whatever steps might be taken, either offensive or defensive.

On the 26th the Second Corps received marching orders and crossed the Appomattox and James to Deep Bottom, to co-operate with the Army of the James. Lieutenant Howell was directed to accompany the movement, and remained with the command until it returned on the night of the 29th to participate in the arrangements for the grand assault upon the enemy's works. Instructions were issued on that day by the commanding general for the guidance of all in the contemplated attack, and in accordance with these engineer officers were assigned to duty with each corps.

On the morning of the 30th the mine was exploded, although, in consequence of some disarrangement of the fuse (Bickford's), not at the appointed hour. The result proved it a decided success, for in its crater were swallowed up several guns, a large number of men-an entire regiment-besides destroying a considerable part of the enemy's line.