The march of Sherman from Atlanta to Savannah and through South Carolina, destroying railroads and supplies,--the taking of Wilmington,--Sheridan's movement from Winchester up the Valley of the Shenandoah, striking the James River Canal and the Central Railroad, and then the transfer of his whole force from the White House to the left flank of the Army of the Potomac,--were parts of a well matured design to weaken Lee's army. Everything was ready for the final blow. The forces of General Grant were disposed as follows. The Army of the James, composed of the Twenty-Fourth and Twenty-Fifth Corps, and commanded by General Ord, was north of the James River, its right flank resting near the old battle-field of Glendale, and its left flank on the Appomattox. The Ninth Army Corps--the right wing of the Army of the Potomac--was next in line, then the Sixth, and then the Second, its left resting on Hatcher's Run. The Fifth was in rear of the Second. The line thus held was nearly forty miles in length, defended on the front and rear by strong earthworks and abatis. General Grant's entire force could not have been much less than a hundred and thirty thousand, including Sheridan's cavalry, the force at City Point, and the provisional brigade at Fort Powhatan. Lee's whole force was not far from seventy thousand,--or seventy-five thousand, including the militia of Richmond and Petersburg; but he was upon the defensive, and held an interior and shorter line. The work which General Grant had in hand was the seizure of the Southside Railroad by an extension of his left flank. He had attempted it once with the Fifth Corps, at Dabney's Mill, and had failed; but that attempt had been of value: he had gained a knowledge of the country. His engineers had mapped it, the roads, the streams, the houses. The fight at Dabney's Mill was a random stroke,--a "feeling of the position," to use a term common in camp,--which enabled him to detect the weak point of Lee's lines. To comprehend the movement, it is necessary to understand the geographical and topographical features of the country, which are somewhat peculiar. Hatcher's Run is a branch of the Nottoway River, which has its rise in a swamp about four miles from the Appomattox and twenty southwest of Petersburg. The Southside Railroad runs southwest from Petersburg, along the ridge of land between the Appomattox and the head-waters of the Nottoway, protected by the swamp of Hatcher's Run and by the swamp of Stony Creek, another tributary of the Nottoway.