It was the railroads, more than the highways, however, which imparted a significance to Petersburg out of all proportion to its size. Confederate leaders were painfully aware that loss of control over their small and harassed network of railroads would mean the loss of the war. Since Petersburg was a point of convergence for five lines, it was of great importance to the South. As other lines of supply were cut off or threatened, the dependence of Richmond upon Petersburg increased. By June 1864 all but one railroad from the south into the Confederate capital--the Richmond and Danville Railroad--passed through Petersburg.
Tracks radiated from Petersburg in all directions. The Richmond and Petersburg Railroad left the city to the north. The Southside Railroad ran west to Lynchburg, while 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 in the direction of Norfolk. For good measure the Petersburg and City Point Railroad struck out for the hamlet of City Point, situated at the junction of the James and Appomattox Rivers 8 miles away. Because of its proximity, Petersburg was a part of the transportation system of the Confederate capital. It served as a major point of transfer to the larger metropolis for products and materials from the vast region to the south.
In the spring of 1862, McClellan had threatened Richmond from the east and southeast. This "Peninsular Campaign" made the defenders of Richmond acutely aware of the need for a system of fortifications around Petersburg. In August of that same year a defense line was begun, and work continued until its completion about a year later. Capt. Charles H. Dimmock 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. It began and ended on the Appomattox River and protected 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. For example, between Batteries 7 and 8 lay a deep ravine 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 of Beauregard, estimated that the long "Dimmock Line" would take more than 10 times as many men to defend as were available.