On April 30, 1863, a Union army commanded by Major General Ulysses S. Grant began crossing onto the east side of the Mississippi River as part of a campaign against Vicksburg.

Early in the American Civil War, the Union military leadership developed the Anaconda Plan, which was a strategy to defeat the Confederate States of America by controlling its coastline and major rivers.

[3] The strategically important city of Vicksburg, Mississippi, was still in Confederate hands, and it served as a strong defensive position that commanded the river and prevented the Union from separating the two halves of the Confederacy.

[7][8] In late November, about 40,000 Union infantry commanded by Major General Ulysses S. Grant began moving south towards Vicksburg from a starting point in Tennessee.

Meanwhile, another arm of the expedition under the command of Major General William T. Sherman left Memphis, Tennessee, on the same day as the Holly Springs Raid and traveled down the Mississippi River.

After diverting up the Yazoo River, Sherman's troops began skirmishing with Confederate soldiers who were defending a line of hills above the Chickasaw Bayou.

[14] Confederate regional commander John C. Pemberton fell for the Union decoys (especially Grierson's Raid), and lost touch with the true tactical situation, believing Grant was withdrawing.

[17] McClernand's corps, which formed the lead element of Grant's army, crossed the river at Bruinsburg, Mississippi, beginning on the morning of April 30.

[18] Brigadier General John S. Bowen, the Confederate commander at Grand Gulf, would be flanked out of the position there if Grant crossed Bayou Pierre.

Bowen moved a portion of his force to Port Gibson to block the Union movements,[19] but he did not have enough troops to destroy Grant's bridgehead and had to hold out for further reinforcements.

[25] The Union won the battle, but the fighting at Raymond led Grant to change his plans; instead of moving directly north, he swung over towards Jackson, Mississippi.

This was intended to disperse a Confederate force gathering there,[26] under the commend of General Joseph E. Johnston, who decided to abandon Jackson in the face of the Union pressure.

[29] Pemberton decided that Johnston's orders were not compatible with a previous directive that he had received from the Confederate President Jefferson Davis that Vicksburg and Port Hudson, Louisiana, should be held.

[31][b] Beginning the offensive, the Confederates started a difficult march slowed by poor road conditions and a washed-out bridge, while Grant moved west in three columns towards Edwards Station.

[36] Major General William W. Loring's Confederate division was cut off during the retreat from the field and withdrew using a different route, separated from the rest of the army.

A bayou ran about 0.75 miles (1.21 km) east of the railroad bridge, cutting its course in front of most of the Confederate line and emptying into the Big Black River at the north end.

[44] Behind the Confederate line but east of the river were a pair of blockhouses that had been built earlier in the year to protect the bridge against cavalry raids.

A secondary bridge was created by turning a small steamboat named Dot crossways in the river where a ferry had existed;[45] the boat's machinery was removed and planks were placed on the decks.

[46] Manning the position was Pemberton's rear guard, which consisted of Brigadier General John C. Vaughn's brigade, Bowen's division, and the 4th Mississippi Infantry Regiment.

[49] Bowen's division was the elite unit of Pemberton's army,[50] but they were exhausted after hard fighting at Port Gibson and Champion Hill and had suffered nearly 1,000 casualties in the latter battle,[51] out of about 4,500 troops engaged.

[53] Colonel Francis M. Cockrell's Missouri brigade held the southern portion of the Confederate line and the area where the Jackson Road crossed it, as Bowen considered this unit to be his best and he expected the Union attack to fall there.

Vaughn's soldiers and the 4th Mississippi were positioned in an area north of the railroad where the Union was least expected to attack, and Brigadier General Martin E. Green's brigade held the far left.

[55] Benton's troops took up a position in the fields east of the woods on the Union right, and Brigadier General Michael Kelly Lawler's brigade formed south of the road.

[64] Grant was confident of victory, and at 8:00 am sent a message to Sherman stating that he believed that the Confederates would be forced to retreat in such a rapid fashion that they could not destroy the bridge.

[65] The Confederates, meanwhile, had such poor morale that Lockett believed the position could not be held; he requested and received permission to prepare the bridge and Dot for burning.

[71] The attack quickly moved across the front of the 1st Missouri Cavalry (dismounted) and out of the regiment's field of fire, although not before Kinsman was killed and the commander of the 21st Iowa, Colonel Samuel Merrill, was wounded.

[82] Albert Lee's soldiers spent the afternoon after the battle in low-intensity fighting across the river against a Confederate force while Carr and Smith's troops patrolled the field.

[95] Loring had noticed light from fires in Union-occupied Edwards on the morning of May 17, and with the way blocked he marched his troops to Jackson, where they joined forces with Johnston on May 19.

[96] McClernand had a replacement bridge built over the Big Black River on the morning of May 18, while McPherson's and Sherman's corps crossed at other points.

Sherman sent a cavalry regiment towards Snyder's Bluff, where the Confederate fortifications were found to have been abandoned, while Grant's army had regained a connection to the Union Navy elements on the Yazoo River.