In preparation for what was likely to transpire, Pemberton had a portion of his army hold the line east of the Big Black River to prevent Loring from being cut off from the main Confederate body at the river crossing. In early May, the Confederate defensive line was laid out by
Samuel H. Lockett. The fortifications were made of cotton bales and dirt. To the south lay Gin Lake: the Confederate right flank was at the lake with the line running north to the Big Black River, which made a bend east of the bridge across it. Both the Jackson Road and the
Southern Railroad of Mississippi ran through the center of the Confederate line and crossed the river. The tracks of the railroad ran on a raised roadbed. While the area west of the bridge contained high hills, the area east of the river was flat. A bayou ran about 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. The Confederate line was just west of the bayou, and trees were felled at the bayou to form an
abatis. The southern portion of the Confederate line contained several artillery positions and faced flat, open fields to the east, while the northern part of the line contained only one artillery position and its
field of fire was obstructed by woods. At the Confederate far left, a smaller set of works had been built east of the bayou, in a position where it could
enfilade a Union advance. This set of works could contain only one regiment. 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; the boat's machinery was removed and planks were placed on the decks. This position was east of Vicksburg. 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. Bowen commanded this 5,000-strong force, which he deemed insufficient to strongly defend the entire Confederate defensive works. The Confederates had 18 cannons. Vaughn's soldiers were inexperienced, mostly conscripts from the
East Tennessee region, whose populace was heavily pro-Union. Although they were fresh, their loyalty to the Confederacy was uncertain. Bowen's division was the elite unit of Pemberton's army, but they were exhausted after hard fighting at Port Gibson and Champion Hill and had suffered nearly 1,000 casualties in the latter battle, out of about 4,500 troops engaged. Pemberton selected Bowen's division for the rear guard as Major General
Carter L. Stevenson's division had already passed through the area and the rest of Pemberton's army was either at Vicksburg or with Loring. 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. If the Confederates were forced to retreat, they would have to cross open ground to the bridge and
Dot, which would become bottlenecks in a retreat. Early on the morning of May 17, McClernand's troops advanced through Edwards and then encountered the Confederate line. His advance was led by the division of Brigadier General
Eugene Carr. Carr's lead brigade was commanded by Brigadier General
William P. Benton, with the
33rd Illinois Infantry Regiment in front as skirmishers. The Illinoisans encountered the Confederate lines, and they then took up a position in the woods facing the north end of the Confederate line. Carr was informed of the encounter and brought up more troops. 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. One of Green's regiments, the
1st Missouri Cavalry Regiment (dismounted), had remained on the far side of the Big Black River, but Bowen now ordered it across the river and into the works on the east side of the bayou. This movement worried Carr, who shifted Lawler to Benton's right, while Brigadier General
Peter J. Osterhaus's division deployed to the south. Brigadier General
Theophilus Garrard's brigade was the left portion of Osterhaus's line, and that of Colonel
Daniel W. Lindsey was to the right. The Union artillery opened fire, and an artillery duel developed. While the Confederate soldiers took cover behind their defenses, the Union soldiers lay flat on the ground, as their position did not provide any cover. Lindsey advanced his brigade west along the railroad , placing his troops ahead of the rest of the Union line. Osterhaus wanted to position Garrard's troops behind Lindsey's, but it was believed that Lawler needed assistance, so two of Garrard's regiments, the
49th Indiana Infantry and
69th Indiana Infantry, were sent to support the Union right. Osterhaus suffered a leg wound during the exchange when Confederate fire exploded an
artillery limber; Osterhaus was replaced by Brigadier General
Albert Lee. 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. 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. Confederate attention was drawn to the center, near the railroad, by the Union artillery fire. Lawler believed that the remains of a
meander scar near the Big Black River would shelter his brigade, and had three regimentsthe
11th Wisconsin Infantry, the
21st Iowa Infantry, and the
23rd Iowa Infantry dash across open ground to reach the depression. Two cannons were positioned in a small clearing between the right of the woods and the Big Black River, and with the
22nd Iowa Infantry Regiment in support. This position allowed Lawler to
enfilade the Confederate position east of the bayou, as well as part of the primary defensive works. This advance was accomplished without many casualties. While these movements were occurring, Brigadier General
Stephen G. Burbridge's brigade of Brigadier General
A. J. Smith's division arrived and was positioned on the Union far left. The two regiments sent from Garrard's brigade took the position previously occupied by the 22nd Iowa, and they also moved into the meander scar. Colonel William Kinsman, the commander of the 23rd Iowa, proposed to Lawler that his regiment should attack the Confederates. Kinsman's reasoning was that the Confederates would only have time to fire one
volley before the Union soldiers reached the defenses, and the Confederates might not put up a stiff fight after the Champion Hill defeat. Lawler ordered a charge by his whole brigade; with the 21st and 23rd Iowa in the front rank while the other two regiments charged behind. His soldiers were ordered not to fire before reaching the Confederate line. 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. The 49th and 69th Indiana joined the attack; while Lawler's soldiers advanced at an angle across Green's front and struck one of Vaughn's regiments, the
61st Tennessee Infantry Regiment. Green's troops fired a volley into Lawler's brigade that the historian Timothy B. Smith describes as "wild and ragged". Lawler's soldiers stopped to fire once they reached the abatis; the Tennesseans were routed and the defenders either ran away or surrendered. Bearss describes the attack, which took three minutes, as one of the shortest of the war. The hole in the Confederate line reached to the railroad, and Green's troops withdrew as well, although some were captured. In the 1st Missouri Cavalry (dismounted), 90 soldiers and the unit's commander, Colonel
Elijah Gates, were captured. Cockrell watched the Confederate left run away and ordered his troops to withdraw, as their position was no longer tenable. Cockrell's retreat became chaotic as well. Confederate artillery west of the river provided covering fire for the retreat. Benton's brigade attacked around the time Lawler broke through the line. Burbridge's and Albert Lee's forces charged the Confederate defenses, only to meet no resistance. Once almost all of the fleeing Confederates crossed the bridge, Lockett had the bridge and
Dot set on fire. He then formed a new line west of the river by using the brigades of Brigadier Generals
Stephen D. Lee and
William E. Baldwin, who had arrived from
Bovina, Mississippi, and part of
Landis's Missouri Battery that had been positioned on the west bank before the battle. Two other Confederate steamboats,
Charm and
Paul Jones, which had been located downstream from the bridge were also burned. 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. The Union reported the capture of 1,751 Confederates as well as 18 cannons. The Confederate artillery losses came about because the horse teams for the cannons had been erroneously moved across the river before the battle for unclear reasons. Green reported having suffered 485 casualties while two of Vaughn's regiments combined for 546 losses. Most of the casualties were prisoners or those missing in action. Few of the casualties occurred before the line fell to pieces. One of Vaughn's regiments, Cockrell's brigade, and the 4th Mississippi did not file casualty reports, but they were known to have suffered heavily in soldiers captured. Union casualties were 279 soldiers killed, wounded, or missing, of which 39 were killed, 237 wounded, and 3 missing. About 200 of the casualties were in Lawler's brigade. Grant's 12-year old son
Fred was wounded in the leg while following the pursuit of the routed Confederates; Fred was present with his father for the entire campaign.
Sergeant William Wesley Kendall of the
49th Indiana Infantry Regiment was awarded the
Medal of Honor for leading a company in the main Union charge; he was among the first Union soldiers to enter the Confederate fortifications. ==Aftermath and preservation==