Big Black River, campaign 1863
While Grant moved north east along the Big Black River towards the state capitol of Mississippi at Jackson, Pemberton was heading in the wrong direction. Convinced that Grant must have a vulnerable supply line connecting him to a base on the Mississippi, Pemberton took 20,000 of his men out of the city and headed south. However, Grant had decided to abandon his supply line, and live off the land. Pemberton wasted 14 May looking for this non-existent supply line. Meanwhile, on the same day Grant defeated Johnston at Jackson, forcing him to retreat south.
On the previous day, Johnston had sent Pemberton a dispatch ordering him to attack Grant’s rear. It took a second order, on 15 May, to force Pemberton to abandon his futile search for Grant’s supply line, and turn back north himself. The same day saw Grant move two of his divisions (McClernand’s and McPherson’s) back to deal with this threat – Johnston’s order had fallen into Federal hands.
By the morning of 16 May, Johnston had got back onto the route between Jackson and Vicksburg, and had taken up a strong position on Champion’s Hill, just over half way from Jackson to the Big Black River. The advance units of Grant’s army discovered this force early that morning. Grant’s men were advancing along three roads, from their positions at Raymond and Jackson towards Edwards Depot, where they had initially expected to find the Confederate force. McClernand was on the left, advancing from Raymond, with McClernand on the right, coming from Jackson. Sherman’s corps remained at Jackson, destroying anything that could help the Confederate war effort.
Most of the fighting took place on the Confederate left. McClernand, a political general not entirely trusted by Grant, did not respond to repeated orders to join the battle, and remained inactive (the Confederate division opposite him only lost 120 men during the entire battle). The bulk of the day’s fighting was carried out by 15,000 of Grant’s 29,000 men. Seven of the nine Confederate brigades present at Champion’s Hill faced one Union army corps.
The fighting that followed was the most severe of the entire campaign. Grant’s attack repeatedly threatened the Confederate left flank, and with it their line of retreat. General Loring, commanding the Confederate forces opposing McClernand, proved to be just as unresponsive to orders, refusing to come to his commander’s aid and giving the presence of McClernand as his reason. His separation from Pemberton was to become complete at the end of the battle, when his line of retreat west was cut off. His division was forced to head east instead, in the hope of finding Joseph Johnston.
Meanwhile, Pemberton’s men had beaten off a series of determined Federal attacks, but their resistance was weakening. Finally, between 3 and 4 in the afternoon another Union attack coincided with a general movement to the left that opened up the Confederate line of retreat. Pemberton took advantage of this and ordered the retreat. It was a rapid and somewhat chaotic retreat, and this is reflected in the high number of Confederate missing. Pemberton lost 378 dead, 1,018 wounded and 2,453 missing or captured, as well as the use of Loring’s division. Union losses were also high, at 410 dead, 1,844 wounded and 187 missing. The higher number of Union dead and wounded reflects their role as the attacker during most of the battle.
Despite the high number of prisoners lost (ten percent of his entire army went missing after the battle!), Pemberton was able to keep his army together, and took up another defensive position on the Big Black River, where he remained until pushed off by Grant on 17 May. After that, his only option was to return to Vicksburg. On 19 May, Grant’s army finally arrived around the Confederate stronghold, and the siege began.