It was the railroads more than the highways, however, which gave to Petersburg a significance out of all proportion to its size. Tracks radiated from the city in all directions. The Richmond and Petersburg Railroad left the city to the north; the Southside Railroad ran west to Lynchburg; the Petersburg and Weldon Railroad led south to North Carolina; the Norfolk and Petersburg Railroad passed through a ravine east of the city before turning southeast toward Norfolk; and the Petersburg and City Point Railroad struck out for the hamlet of City Point, situated at the junction of the James and Appomattox Rivers about 8 miles away.

Because of its proximity, Petersburg became a part of the transportation system of the Confederate capital, serving as a major point of transfer to the larger metropolis for products and materials from the vast regions to the south and southwest. By June 1864, all but one railroad from the south and west into Richmond—the Richmond and Danville Railroad—passed through Petersburg. As other lines of supply were cut off or threatened, the dependence of Richmond upon Petersburg increased and made the security of that city a matter of vital concern.

In the spring of 1862, McClellan’s Peninsular Campaign had threatened Richmond from the east and southeast, making that city’s defenders acutely aware of the need for a system of fortifications around Petersburg. In August a defense line was begun, and work continued until its completion about a year later. Capt. Charles H. Dimmock, a Northerner by birth, was in charge of it under the direction of the Engineer Bureau, Confederate States Army, and the line so constructed became unofficially known as the “Dimmock Line.”

When finished, the chain of breastworks and artillery emplacements around Petersburg was 10 miles long, beginning and ending on the Appomattox River and protecting all but the northern approaches to the city. The 55 artillery batteries were consecutively numbered from east to west. Although natural terrain features were utilized whenever possible, some glaring weaknesses existed, such as the deep ravine between Batteries 7 and 8, which could provide a means of penetration by an attacking force. The very length and size of the fortifications proved to be a disadvantage. It meant that a larger number of troops would be necessary to defend the line than General Beauregard, charged with this heavy responsibility, had present for duty. Col. Alfred Roman, an aide-de-camp to Beauregard, estimated that the long “Dimmock Line” would require more than 10 times as many men to defend it as were available.

On several occasions raids were made on the railroads south and west of Petersburg. The most serious of these occurred on June 9, 1864, when 3,000 infantry and 1,300 cavalry appeared in force along the eastern and southeastern sector of the Dimmock Line. The infantry contented itself with a menacing demonstration, but the cavalry attacked up the Jerusalem Plank Road. After breaking through the defenses, the horse soldiers were checked by regular Southern army units assisted by a hastily summoned home guard of old men and youths. The damage done by such raids was quickly patched up, but they were a constant nuisance to the city’s transportation lines. To shut off permanently the supplies that streamed along the railroads, the Union forces would have to take permanent physical possession of them.