Next morning (17th) the enemy was vigorously pursued to the banks of the Black River, where they made a stand to cover the passage of their train and artillery across that stream. Besides the railway bridge, Pemberton had a bridge which consisted mainly of three steam-boats, but he was not able to get all his impedimenta over the river. Carr's division and Lawler's brigade carried the Confederate defences after a fight of about two hours, and Pemberton fled in the direction of Vicksburg, leaving 18 guns, 1,500 prisoners, several thousand stand of arms, and large quantities of commissary stores, to fall into the Union hands. The loss of Grant's forces in the affair of the Black River was 29 killed and 242 wounded. Pemberton burned the bridges as he retired, and thus delayed pursuit. McClernand and McPherson built bridges during the night, and the 15th corps, which had the only pontoon train, crossed at Bridgeport several miles above.
Each corps began crossing at eight a.m. on the 18th, the 15th pressing forward to within 3½ miles of Vicksburg, when it turned to the right and occupied Walnut Hills to open communication with the Yazoo. McPherson followed the route of the 15th corps to where it turned off to the right, and there he halted for the night. McClernand advanced on the direct road from Jackson to Vicksburg, and when near the city turned to the left. On the morning of the 19th the investment of the city was practically completed, though there were several gaps to be filled in the lines of the besiegers. Vicksburg was in a state of siege.
Communication was opened with the gun-boat fleet, which had been guarding the front of Vicksburg and preventing the receipt of supplies by river. The gun-boats then ascended to attack Haines' Bluff, which the Confederates immediately evacuated, as their position was no longer tenable with the Union forces in their rear. The fortifications at Haines' Bluff were found to be strongly
