Gen. Joseph E. Johnston, commanding Confederate military operations in the West. Courtesy National Archives.
THE BATTLE OF PORT GIBSON.
McClernand’s Corps, immediately upon debarking on April 30, headed for the bluffs 3 miles inland. By nightfall the Federal soldiers had reached the high ground and pushed on toward Port Gibson, 30 miles south of Vicksburg. From this point, roads led to Grand Gulf, Vicksburg, and Jackson. Maj. Gen. John S. Bowen moved his Grand Gulf command toward Port Gibson to intercept the threat, and, at daylight on May 1, leading elements of the Union advance clashed with Bowen’s troops, barring the two roads which led to Port Gibson.
The battle of Port Gibson was a series of furious day-long engagements over thickly wooded ridges cut by deep, precipitous gullies and covered with dense undergrowth. While greatly outnumbering Bowen, McClernand was prevented by the rugged terrain from bringing his whole force into action. Slowly forced backward, Bowen conducted an orderly retreat through the town, which he evacuated. The holding action had cost Bowen 800 casualties from his command of 8,000; Union losses were about the same from a force at hand of about 23,000. Pemberton determined not to contest Grand Gulf lest he risk being cut off from Vicksburg and withdrew across the Big Black River. Thus he permitted Grant to occupy Grand Gulf and gave him a strong foothold on the east bank of the Mississippi.
THE STRATEGY OF THE VICKSBURG CAMPAIGN.
Grant’s overall strategy, up to the capture of Grand Gulf, had been first to secure a base on the river below Vicksburg and then to cooperate with Maj. Gen. Nathaniel P. Banks in capturing Port Hudson. After this he planned to move the combined force against Vicksburg. Port Hudson, a strong point on the Mississippi near Baton Rouge, was garrisoned by Confederate troops after Farragut’s withdrawal the previous summer. At Grand Gulf, Grant learned that Bank’s investment of Port Hudson would be delayed for some time. To follow his original plan would force postponement of the Vicksburg campaign for at least a month, giving Pemberton invaluable time to organize his defense and receive reinforcements. From this delay the Union Army could expect the addition of no more than 12,000 men. Grant now came to one of the most remarkable decisions of his military career.
Information had been received that a new Confederate force was being raised at Jackson, 45 miles east of Vicksburg. Against the advice of his senior officers, and contrary to orders from Washington, Grant resolved to cut himself off from his base of supply on the river, march quickly in between the two Confederate forces, and defeat each separately before they could join against him. Meanwhile, he would subsist his army from the land through which he marched. The plan was well conceived, for in marching to the northeast toward Edwards Station, on the railroad midway between Jackson and Vicksburg, Grant’s vulnerable left flank would be protected by the Big Black River. Moreover, his real objective—Vicksburg or Jackson—would not be revealed immediately and could be changed to meet events. Upon reaching the railroad, he could also sever Pemberton’s communications with Jackson and the East. It was Grant’s belief that, although the Confederate forces would be greater than his own, this advantage would be offset by their wide dispersal and by the speed and design of his march.
But this calculated risk was accompanied by grave dangers, of which Grant’s lieutenants were acutely aware. It meant placing the Union Army deep in alien country behind the Confederate Army where the line of retreat could be broken and where the alternative to victory would not only be defeat but complete destruction. The situation was summed up in Sherman’s protest, recorded by Grant, “that I was putting myself in a position voluntarily which an enemy would be glad to maneuver a year—or a long time—to get me.”
The action into which Pemberton was drawn by the Union threat indicated the keenness of Grant’s planning. The Confederate general believed that the farther Grant campaigned from the river the weaker his position would become and the more exposed his rear and flanks. Accordingly, Pemberton elected to remain on the defensive, keeping his army as a protective shield between Vicksburg and the Union Army and awaiting an opportunity to strike a decisive blow—a policy which permitted Grant to march inland unopposed.