This map is based on one given in Donald Pfanz's biography of Confederate Lt. Gen. Richard S. Ewell, who commanded the Department of Richmond for much of the siege. The map was intended to show the Federal plan of attack during the Fort Harrison operation of late September, 1864, but it also serves to establish the road network north of the James and its relationship to the Federal bridgehead at Deep Bottom and the Confederate lines in front of Richmond and along the James. The notation "FH" shows the position of Fort Harrison; the Interior Line of defenses is just off the upper left corner of the map.

In the aftermath of the Fort Harrison operation, the Federals drew a line of works close up to the Confederate Exterior Line all the way from Signal Hill to Fort Harrison (which the Federals renamed Fort Burnham, in honor of Brig. Gen. Hiram Burnham, killed in the fighting on September 29, 1864), across the Varina Road and then across the New Market Road. A line of detached forts covered the Federal flank along the New Market Road and almost connected with a second line of defenses covering the Deep Bottom bridgehead.

An active Federal presence north of the James was a serious threat to Lee's position. Federal troops here could make easy use of the Darbytown, Charles City, and Williamsburg Roads to advance on Richmond, forcing Lee to keep more troops here than heretofore had been the case. This was the logic behind Weitzel's ill-fated attack in late October, 1864.