The first battle during General U.S. Grant’s successful campaign against the Confederate stronghold of Vicksburg on the Mississippi (American Civil War). On 16 April, a small naval force had run past the Vicksburg guns, to be followed on 22 April by barges and transports. Although six of twelve barges were sunk by the Confederate guns, this still gave Grant enough shipping to transport a large part of his army from the west bank of the Mississippi over to the east bank south of Vicksburg, from where the city could be attacked.
On 30 April, the first of Grant’s men, from McClernand’s corps, were ferried across the river to Bruinsburg. Although this was what Grant had been working for since the previous December, this was also the most dangerous moment of the campaign. General Pemberton, the Confederate commander in Vicksburg, temporarily outnumbered Grant, and if he launched an attack now with all available men then Grant would be in serious trouble. Pemberton could have raised 30,000 men against the 23,000 Grant had so far managed to ship across the river. Instead, Pemberton remained at Vicksburg, determined not to risk losing the city to a sudden raid.
That meant that the only Confederate force close to Grant was one of 6,000 men at Port Gibson, ten miles inland from the Mississippi. This force was the garrison of Grand Gulf, where Grant had initially wanted to land, which had moved south to oppose Grant’s landing. Instead it found itself under attack.
Despite being badly outnumbered, the Confederate defenders of Port Gibson had the advantage of terrain. Approaching from the south, Grant had to send troops along two different roads into the town, each running along a ridge, and separated by a deep ravine. These ridges were to play a major part in the later siege of Vicksburg. For the moment they allowed the Confederates to push back the Union left, with heavy losses.
Grant’s superior numbers now carried the day. He was able to order a full brigade to cross yet another ravine to a third ridge, thus threatening to outflank the Confederate defenders. This flanking manoeuvre must have distracted the Confederates, for another frontal attack by the Union left wing now met with success. The Confederate force now retreated back towards Grand Gulf. That night Grant’s men camped two miles north of Port Gibson.
Federal losses were surprisingly heavy, at 131 killed, 719 wounded and 25 missing. Only Champion’s Hill, the biggest battle of the campaign, saw more Union losses. The Confederates lost their best chance to fight Grant with the advantage of numbers. The garrison of Grand Gulf withdrew to Vicksburg, to avoid being cut off. Grant was now free to turn his attention east, to the forces being gathered to reinforce Vicksburg. These he was to defeat in the Big Black River campaign.