Champion Hill occurred. Lieutenant General John C. Pemberton had concentrated most of his Confederate army to attempt to block Grant's army from reaching Vicksburg. Union attacks drove in much of the Confederate line, although a counterattack by Bowen's division threatened to change the tide of the battle. Eventually, Union reinforcements forced Bowen to retreat, and the Union had control of the field. Battle On the night of the 16th, after the defeat at Champion Hill, Pemberton formed a line at the crossing of the Big Black River in order to buy time for his army. For this rear guard, Pemberton selected the Missouri troops of Bowen's division, Brigadier General John C. Vaughn's Tennessee brigade, and the 4th Mississippi Infantry Regiment. This force numbered about 5,000 men. The left of the Confederate line was held by Brigadier General Martin E. Green's brigade of Bowen's division, Vaughn's brigade held the center, Bowen's other brigade, commanded by Colonel Francis M. Cockrell, was positioned on the Confederate right, and the 4th Mississippi was placed between Cockrell and Vaughn. Vaughn's brigade was composed of inexperienced conscripts, and Bowen's division had seen heavy fighting at Champion Hill. The Confederate line was supported by Wade's Missouri Battery, Landis' Missouri Battery, and Guibor's Missouri Battery. A railroad ran through the Confederate position, and the river could be crossed either over the railroad bridge or over a steamboat that had been positioned crossways across the river, creating a makeshift bridge. On the morning of May 17, McClernand's XIII Corps advanced towards the Confederate position at the Big Black River. Brigadier General Eugene A. Carr's division led the way, and deployed to confront the Confederate lines. The brigade of Brigadier General Michael K. Lawler formed the right of the Union line. Carr was soon reinforced by Brigadier General Peter J. Osterhaus' division. An artillery duel began, and Osterhaus was wounded in the leg by a shell fragment. After some preparations, Lawler's brigade charged, quickly breaking the Confederate line. Vaughn's brigade routed to the rear, and the gap in the line quickly forced Green's brigade to retreat as well. Lawler's charge had lasted only three minutes. Cockrell's brigade also collapsed in much disorder, one survivor summarized the retreat as "the devil take the hindmost being the order of the day." The 1st and 4th Missouri Infantry Regiment (Consolidated) served as a rear guard for the retreating Confederates, as it was one