It is unnecessary for me to remind you of the overwhelming importance of celerity in your movements. The enemy is badly beaten, greatly demoralized, and exhausted of ammunition. The road to Vicksburg is open. All we want now are men, ammunition, and hard bread. We can subsist our horses on the country, and obtain considerable supplies for our troops.The situation was not as good for the Federals as Grant thought. The Confederates would not give up Vicksburg without a hard fight. Reinforcements were on the way to reinforce Pemberton, and he pulled his men back north to limit the territory they would have to defend. This would lengthen Grant's supply line even farther, making it harder and harder to keep his men fed. However, Pemberton miscalculated. Like Scott had done in the Mexican American War, Grant would not depend on his supply line. Through carefully managed logistics, he would bring up a few necessary supplies and for the rest would live off the country and what he could carry in wagons. He would capture Jackson, Mississippi first, and destroy it as a railroad hub, at which point he could turn on Vicksburg without having to worry about an army in his rear. McClernand would move up the Big Black River between Jackson and Vicksburg, while McPherson moved directly on Jackson, leaving Sherman in reserve.
McPherson encountered the Southern troops around Raymond on May 12th. They were 4000 Confederate troops under John Gregg. McPherson alone had three times this number. Gregg planned to attack what he originally thought was only a raiding party by ambushing and surrounding them after they crossed Fourteen mile creek. The first division McPherson sent forward was disorganized by the terrain. The creek was very shallow, but it was in a deep gorge and the area was covered with vines and thorns. When the Confederates charged with their terrible rebel yell, the Federals retreated, but they rallied and engaged in a hot fight with the Confederates at very close range. When the regiments Gregg had sent to get in the Yankee's rear were in position, they found the plan was impractical because they were fighting an entire corp, instead of the raiding party they expected. The Confederates would not be able to hold their position for long, and a retreat was ordered. Half of a regiment fought as a rear guard against the Union division, allowing many Confederates to escape from the disorganized battle. The Confederates fell into disorder before the large number of Federal troops, but Gregg threw in his reserves and rallied his fleeing men. He was able to delay McPherson long enough for his outnumbered and battered men to be able to retreat safely.