Brigadier General John Gregg was tasked with commanding the Confederate rear guard, which fought Sherman's and McPherson's men at Jackson on May 14 before withdrawing.

Despite being reinforced, Johnston made only a weak effort to save the Vicksburg garrison, and was driven out of Jackson a second time in mid-July.

[1] Grant's men fought their way inland and then moved east with the intention of later turning to the west and attacking Vicksburg from that direction.

During his journey to Jackson, Johnston had learned that Grant's army had moved into Mississippi, while Pemberton's force was holding a defensive position along the Big Black River.

[7] Johnston decided that Jackson could not be held in what the historians William L. Shea and Terrence J. Winschel described as "unseemly haste", sent a telegram to his commanding officers in Richmond, Virginia, stating "I am too late", and ordered the evacuation of the city.

[10] Two Confederate officers, Brigadier General W. H. T. Walker and Colonel Peyton Colquitt had formed a roadblock outside of town with their brigades, but the rainfall forced the action to halt.

During the respite provided by the rain, the Confederates learned of Sherman's approach, and sent a unit of mounted infantry to confront his column.

[12] McPherson, unsure of the strength of the force he was facing, initially acted cautiously, using artillery fire to probe the Confederate lines.

After determining that he was not facing a large force, McPherson ordered Brigadier General Marcellus M. Crocker's division to attack the Confederate lines.

Only small amount of artillery fire resisted his advance, and Sherman detached the 95th Ohio Infantry Regiment to test the Confederate fortifications.

The Ohio regiment found that the position had been abandoned, and were informed by an African American civilian that only a token Confederate artillery force remained.

Named the Army of Relief, Johnston's force did not move against Grant until July 1, and then upon reaching the Union lines at the Big Black River two days later, decided that the defenses could not be taken and did not bring on a battle.

[23] The City of Jackson preserves 2 acres (0.81 ha) of the battlefield: one in a public park and another on the campus of the University of Mississippi Medical Center.