distance, and a great portion of the bridge could be built on trestles, whereas, in the James River
construction, only about two hundred feet could be built of trestling.
On July 9, 1864, an order was issued directing operations against Petersburg
by regular siege-works.
This required a survey of the topography of the country and the positions of the lines of both armies.
A map was made by the engineers which was constantly used as a reference by all the officers concerned in laying out and constructing these works.
The engineers planned the regular entrenchments and approaches as far as possible, but, because of the multiplicity of duties devolving upon them, much of this work was delegated to other officers, who closely followed the plans indicated on the maps furnished.
At noon, on June 25th, a mine was begun by the troops in front of Petersburg
This was not undertaken by engineer troops, but was under the direction of Lieutenant-Colonel Henry Pleasants
, Forty-eighth Pennsylvania Volunteers, and was executed by his own men. General Meade
and General Grant
sanctioned the project, and plans were adopted for an assault on the entire Confederate line when the mine should explode.
The majority of the men employed in the work were miners from the coal regions of Pennsylvania
, and the necessary expedients were familiar to them, without special instructions from the engineers.
The excavation was commenced without special tools, lumber, or any of the materials usually required for such work.
By late afternoon, on July 23d, the excavations were deemed complete.
Eighteen thousand cubic feet of earth had been removed.
The mine was charged on the afternoon and evening of the 27th, with three hundred and twenty kegs of powder, each containing about twenty-five pounds. Altogether, there were eight magazines connected by wooden tubes which were half filled with powder.
These tubes met at the inner end of the main gallery, and fuses were laid along this gallery to the exit.