Battle of Port Gibson

The Battle of Port Gibson (May 1, 1863) was fought between a Union Army commanded by Major General Ulysses S. Grant and a reinforced Confederate States Army division led by Major General John S. Bowen. Though the outnumbered Confederate soldiers fought stubbornly, they were steadily pressed back during the day by Major General John A. McClernand's troops. Bowen eventually conceded the field by withdrawing north toward Vicksburg, Mississippi. The battle occurred near Port Gibson, Mississippi, during the Vicksburg Campaign of the American Civil War.

Starting in November 1862, Grant tried various strategies in order to attack Vicksburg, and in each case, his army was unsuccessful. Finally, Grant ordered his army to march through swampy terrain on the west bank of the Mississippi River in an attempt to get south of Vicksburg. The Union commander gambled that the Union Navy under Acting Rear Admiral David Dixon Porter could safely pass the Vicksburg batteries. The operation was successful, and Porter's gunboats and river transports carried the first two army corps of Grant's army to the east bank. Meanwhile, Grant's third corps threatened Vicksburg from the northwest. The Confederate commander Lieutenant General John C. Pemberton was caught with his army scattered and could only oppose Grant with inferior forces at Port Gibson. This was the first of several Union victories in May 1863 that would result in the Siege of Vicksburg.

Grant assumed command of the Army of the Tennessee on October 25, 1862, and started the Vicksburg campaign a week later. Grant's first foray with 40,000 soldiers came to grief when Major General Earl Van Dorn's cavalry wrecked his supply base in the Holly Springs Raid on December 20. At the same time, a 32,000-man riverine expedition led by Major General William Tecumseh Sherman was repulsed at the Battle of Chickasaw Bayou on December 27–29. When McClernand arrived to assume command, Sherman suggested a thrust up the Arkansas River supported by Porter's Mississippi River Squadron. The result was a Union victory at the Battle of Arkansas Post on January 11, 1863. For a Federal loss of 1,061 casualties, about 4,900 Confederates were captured. When Grant learned about the divergent expedition, he ordered the troops back to the Mississippi River.

These events were followed by the unsuccessful Yazoo Pass and Steele's Bayou expeditions in March 1863. Grant also tried to dig several canals to create a water-borne route west of the Mississippi River that would avoid the Vicksburg batteries; all were eventually abandoned. When newspaper editors and politicians demanded Grant's removal from command, President Abraham Lincoln replied, "I can't spare this man, he fights". Earlier in the campaign, Lieutenant Colonel James H. Wilson of Grant's staff suggested having Porter's fleet run past the Vicksburg batteries at night. After this, the army would march downstream from Vicksburg on the west bank of the Mississippi River and be ferried across to the east bank. All of Grant's subordinate commanders were against it. Having tried every other approach, Grant determined to execute this plan. He gambled that Porter's squadron could accomplish its part.

The Union XIII Corps was formed on October 24, 1862, and assigned to Grant. On December 18, the XIII Corps was split into four new formations: XIII Corps, XV Corps, XVI Corps, and XVII Corps. The commanders were McClernand for the XIII Corps, Sherman for the XV Corps, Major General Stephen A. Hurlbut for the XVI Corps, and Major General James B. McPherson for the, XVII Corps. Hurlbut's XVI Corps guarded Memphis, Tennessee, until June 1863, leaving the other three corps as Grant's field army. McClernand's corps numbered over 17,000 men, McPherson's counted 16,000 soldiers, and Sherman's corps had slightly under 17,000 troops. The four XIII Corps divisions were led by Brigadier Generals Peter J. Osterhaus, Andrew Jackson Smith, Alvin P. Hovey, and Eugene Asa Carr. The three XV Corps divisions were commanded by Brigadier Generals Frederick Steele, Francis Preston Blair Jr., and James M. Tuttle. The three XVII Corps divisions were led by Major General John A. Logan and Brigadier Generals John McArthur and Marcellus M. Crocker. The XIII Corps divisions had two brigades each while the XV and XVII Corps divisions had three brigades each.

Pemberton took command of the Department of Mississippi and East Louisiana on October 14, 1862. Pemberton's Army of Mississippi consisted of five infantry divisions. These were led by Bowen and Major Generals Martin Luther Smith, John Horace Forney, William Wing Loring, and Carter L. Stevenson. Bowen's division had 4,500 soldiers, Smith's had 3,500, Forney's had 5,500, Loring's had 7,800, and Stevenson's had 12,000. Pemberton also controlled the artillery batteries at Vicksburg under Colonel Edward Higgins.

On March 29, 1863, Grant ordered McClernand's XIII Corps to move south from Milliken's Bend to New Carthage which was south of the fortifications at Vicksburg and Warrenton. Osterhaus' division occupied Richmond, Louisiana, on March 31. Brushing aside a few hundred Confederates led by Major Isaac F. Harrison, Osterhaus' troops moved through swampy terrain along Roundaway Bayou and occupied New Carthage on April 6. McClernand continued shifting his corps to New Carthage, which entailed repairing broken levees and corduroying the muddy roads. On April 15, Harrison, reinforced by 1,800 of Pemberton's soldiers, tried to evict the Federals from New Carthage but failed.

On the night of April 16, 1863, Porter's squadron began its attempt to pass Vicksburg. Porter in the ironclad USS Benton led the warships USS Carondelet, USS Lafayette, USS Louisville, USS Mound City, USS Pittsburgh, and USS Tuscumbia, and three river transports towing barges loaded with supplies. For two hours, the Vicksburg batteries shelled the Union fleet, hitting each vessel numerous times. However, except for one transport which caught fire and burned, the vessels were not seriously damaged and only 14 men were wounded. Grant ordered McPherson to move the XVII Corps south from Lake Providence to Richmond. Once the XVII Corps was south of Vicksburg, Sherman's XV Corps would follow. Supply depots on the west bank of the Mississippi River were garrisoned by hastily recruited and trained African American soldiers led by white officers.