"Move your command tonight to the next cross-roads if there is water, and tomorrow with all activity into Raymond."
Maj. Gen. Grant to Maj. Gen. McPherson, USA, May 9, 1863
"Move your brigade promptly to Raymond, taking three days' rations, and carrying only cooking utensils and ammunition; no baggage ... Use Wirt Adams' cavalry at Raymond for advance pickets."
Lt. Gen. John C. Pemberton, May 10, 1863
General Grant successfully transferred his army onto the east side of the Mississippi River and was marching northeast from Port Gibson to attack Vicksburg from the east. His 48,000 men were spread out along several roads headed for a stretch of the Southern Railroad of Mississippi between Edwards and Clinton. Grant's objective was simple: destroy the railroad—Vicksburg's lifeline—and then turn on Lt. Gen. John C. Pemberton and Vicksburg.
The far right, or eastern flank of Grant's army was Maj. Gen. James B. McPherson's XVII Corps. At 3:30 in the morning of May 12, 1863, these 12,000 soldiers set out on their nine-mile march from Roach's plantation to Raymond, where they hoped to find drinking water and a Confederate commissary.
Meanwhile, Confederate Brig. Gen. John Gregg arrived in Raymond on May 11 after an arduous eight-day, two-hundred-mile journey and, without accurate information, assumed that the Federal column coming up the Utica Road toward Raymond was only a brigade with perhaps 1,600 men. He positioned his troops south of Raymond to intercept and capture this isolated wing of Grant's army.
The boldness of John Gregg's actions at Raymond on May 12, 1863, convinced Grant that the Confederate forces in the Jackson vicinity had grown too large to be ignored. Thinking he was now caught between two Confederate armies, Grant audaciously split his forces, he protected the rear of his army with one corps and with the other two attacked Jackson, dispersing one Confederate army and destroying the two railroads that intersected there.