Port Gibson

On May 1, 1863, forces under Major General Ulysses S. Grant clashed with a reinforced Confederate division under Major General John S. Bowen near Port Gibson, Mississippi, in what became known as the Battle of Port Gibson. Although badly outnumbered, Bowen's men resisted fiercely, yet Major General John A. McClernand's troops gradually forced them backward as the hours wore on. By day's end Bowen had no choice but to give up the ground and retreat northward toward Vicksburg. This clash formed part of the broader Vicksburg Campaign of the Civil War.

Grant had spent months since November 1862 searching for a way to strike Vicksburg, and every attempt up to that point had failed. He then made the decision to send his army through difficult, swamp-choked ground along the western side of the Mississippi River, hoping to position his forces south of the city. Success depended on a risky bet: that Acting Rear Admiral David Dixon Porter's naval squadron could slip past the guns defending Vicksburg without being destroyed. That gamble paid off, and Porter's gunboats along with river transports ferried the leading two corps of Grant's army across to the eastern bank. At the same time, a third corps under Grant kept pressure on Vicksburg from the northwest. Confederate commander Lieutenant General John C. Pemberton found his troops spread thin and lacked the concentrated strength to meet Grant on equal terms, leaving only a weaker force to defend Port Gibson. This engagement marked the opening Union triumph in a string of victories throughout May 1863 that would ultimately lead to the Siege of Vicksburg.

Background

Taking charge of the Army of the Tennessee on October 25, 1862, Grant launched his push toward Vicksburg only seven days afterward. His initial attempt, involving 40,000 troops, collapsed when Major General Earl Van Dorn's horsemen destroyed his supply depot during the Holly Springs Raid on December 20. Around this same period, Major General William Tecumseh Sherman led a 32,000-strong river-based force that met defeat at Chickasaw Bayou from December 27 through 29. Once McClernand took over command, Sherman proposed advancing up the Arkansas River with help from Porter's Mississippi River Squadron, an idea that produced a Union triumph at Arkansas Post on January 11, 1863. Roughly 4,900 Confederate soldiers fell into Union hands there, while Federal losses totaled 1,061. Upon hearing of this separate operation, Grant recalled the men to the Mississippi.

March 1863 brought further setbacks in the form of the failed Yazoo Pass and Steele's Bayou expeditions. Grant additionally attempted to excavate canals that would bypass the Vicksburg defenses via a route on the river's western side, though every such effort was eventually scrapped. As criticism mounted from the press and political figures calling for his dismissal, President Abraham Lincoln declared, "I can't spare this man, he fights." Earlier on, Lieutenant Colonel James H. Wilson, a member of Grant's staff, had floated the idea of sending Porter's ships past the Vicksburg guns under cover of darkness, after which the army would march down the river's west bank below the city and cross over to the eastern shore. Despite unanimous opposition from his subordinate generals, Grant, having exhausted other options, committed to this scheme, wagering that Porter's naval force could pull off its portion of the mission.

On March 29, 1863, McClernand's XIII Corps received orders from Grant to head south from Milliken's Bend toward New Carthage, a point beyond the Vicksburg and Warrenton defenses. By March 31, Osterhaus and his division had taken Richmond, Louisiana. After sweeping aside several hundred Confederates under Major Isaac F. Harrison, Osterhaus's men pushed through marshland along Roundaway Bayou and secured New Carthage on April 6. As McClernand continued relocating his corps there, his men had to mend collapsed levees and lay corduroy across muddy roads. Reinforced with 1,800 troops from Pemberton, Harrison attempted on April 15 to drive the Federals out of New Carthage but did not succeed.

Porter's fleet made its attempt to slip past Vicksburg on the night of April 16, 1863. Aboard the ironclad USS Benton, Porter guided a group that included the USS Carondelet, Lafayette, Louisville, Mound City, Pittsburgh, and Tuscumbia, along with three transport vessels hauling supply-laden barges. Vicksburg's guns bombarded the fleet for a two-hour stretch, striking every ship multiple times, yet aside from one transport that burned after catching fire, the vessels escaped serious harm, with only 14 sailors wounded. Meanwhile, Grant directed McPherson to bring the XVII Corps down from Lake Providence to Richmond, with Sherman's XV Corps set to follow once McPherson's men had cleared the area south of Vicksburg. African American soldiers, newly enlisted and trained and commanded by white officers, guarded the supply depots along the Mississippi's west bank.

Recognizing that the muddy road on the west bank could not sustain his army's supply needs, Grant arranged a second convoy. On the night of April 22, six transports, unaccompanied by escorts and each towing barges carrying 100,000 rations along with other provisions, attempted the same passage. This run also succeeded, though the lead vessel, a hospital ship, sank and two men lost their lives. During this period, McClernand's corps pressed southward, cutting fresh roads through swampland as needed, and gained the support of one division from McPherson's command. McClernand, who had brought his new wife with him and was notoriously hard to manage, required constant pressure from Grant to keep moving.

Grant then instructed Porter

Aftermath

Exhaustion from marching inland and fighting through the day left Union troops too spent to chase the retreating enemy. Grant wanted to press the fight again, but by the following morning his opponents had slipped away. McClernand's men took control of Port Gibson, a vital road hub, early on May 2. Bowen had hoped to hold the crossing at Bayou Pierre, but with no reinforcements coming, he gave up that ground. Command of Bowen's men soon passed to Loring, who pulled the troops back beyond the Big Black River. The Confederates abandoned Grand Gulf as well, destroying its powder magazines before leaving. Pemberton had a chance here to pull his army together for a decisive clash with Grant, but he hesitated instead of acting. By May 4, Grant's forces stood north of Bayou Pierre, and he shifted his supply base from Bruinsburg to Grand Gulf.

At Grand Gulf, Grant held his position while waiting for Sherman's XV Corps, which arrived on May 7. Under the original strategy, the XIII Corps was supposed to head south and assist Major General Nathaniel P. Banks in taking the Confederate stronghold of Port Hudson, Louisiana. But Banks had not yet reached that objective; his troops were still advancing north from Opelousas, with the lead elements only arriving at Alexandria that same day, May 7. Realizing Banks was nowhere near Port Hudson, Grant chose to keep McClernand's corps under his own command and pursue an independent campaign instead. Lacking a dependable supply route, he resolved that his men would forage for what they needed from the countryside. On May 6, before Sherman's troops had even caught up, Grant set his army moving northeast along the southern bank of the Big Black River, aiming to sever the rail line linking Vicksburg and Jackson. A string of further victories followed, and by May 19 Grant's forces had encircled Pemberton's army, beginning the Siege of Vicksburg.