Petersburg was at the junction of three railroads, and was a place of great importance to the Confederacy, as all the supplies of Lee's army, as well as to Richmond, came by the way of Petersburg, and for these reasons General Grant resolved to destroy the railroads, and if possible to capture the city, and thus destroy the Confederates' source of supplies.
These conditions being well known to Lee, he resolved to defend Petersburg, and to save it from capture if possible, and thus began the greatest struggle of its kind known in modern times.
The advance divisions of Grant's army, under Hancock and W. F. Smith, appeared before Petersburg June 15, 1864. Beauregard managed to hold the entrenchments with his small force until Lee's main army arrived, which came by a shorter route than the one which the Federals had taken. Both armies were in full force before Petersburg by the evening of the 18th, and the great struggle had now begun. The Confederate entrenchments extended for thirty miles, and the whole country was a network of fortifications. Grant at once began to extend his lines of entrenchments, and thus the two armies were pitted against each other for their last great struggle, the army of General Grant numbering more than 100,000 men, while that of General Lee was about half that number.
General Grant turned his attention to trying to destroy the railroads, and made several attempts with much hard fighting to do so. But this, having been anticipated by General Lee, he had given to A. P. Hill the defense and the protection of the railroads, which was his source of supplies. They were ably protected by General Hill, and Grant's attacking parties in every instance were repulsed, and these plans were at length abandoned by him for the present.
The two armies lay facing each other before Petersburg the entire summer and fall, with several small engagements during the summer and a few very severe ones.
A severe cavalry engagement was fought at Trevilian Station, north of Richmond, on June 11th, between the Confederates, commanded by Generals Hampton and Fitzhugh Lee, and the Federals, commanded by General Sheridan.
During the latter days of July the Federals were engaged in digging a mammoth tunnel, beginning in the rear of their entrenchments and to extend under the Confederate fortifications before Petersburg, at the completion of which they expected to fill the same with large quantities of gunpowder which was to be exploded and was expected to blow up the Confederate fortifications.
Of all the schemes employed by either army this was the greatest, and one in which Grant had great faith, and the progress of which was watched with great anxiety. The Confederates were apprised of this undertaking, and had made ready by placing several batteries within their lines so that the fire from the same would sweep the opening which would be made by the blowing up of the "crater." At a few minutes past five on the morning of July 30th this mine was exploded, which was a sight to behold. The Federal troops who were in waiting to march through the opening were somewhat delayed from the shock and horror of the explosion, but at length marched in the opening in great numbers, and by this time the Confederate batteries were brought into action, which so horribly swept their ranks, and they were charged by General Mahone with several divisions of Georgia troops, and the Federal loss became so great, and their ranks in so much confusion, that they were ordered to retire within their entrenchments, thus bringing to a dismal failure the capture of Petersburg by this plan.
BATTLE OF SPOTTSYLVANIA COURT-HOUSE