Following the failure of the May 22, 1863 assault, Grant realized that Vicksburg could not be taken by storm and decided to lay siege to the city. Slowly his army established a line of works around the troubled city and cut Vicksburg off from supply and communications with the outside world.
Commencing on May 26, Union forces constructed thirteen approaches along their front aimed at different points along the Confederate defense line. The objects was to dig up to the Confederate works then tunnel underneath them, plant charges of black powder, and destroy the fortifications. Union troops would then surge through the breach and gain entrance to Vicksburg.
Throughout the month of June, Union troops advanced their approaches slowly toward the Confederate defenses. Protected by the fire of sharpshooters and artillery, Grant’s fatigue parties neared their objectives by late June. Along the Jackson Road, a mine was detonated beneath the Third Louisiana Redan on June 25, and Federal soldiers swarmed into the crater attempting to exploit the breach in the city’s defenses.
The struggle raged for 26 hours during which time clubbed muskets and bayonets were freely used as the Confederates fought with grim determination to deny their enemy access to Vicksburg. The troops in blue were finally driven back at the point of bayonet and the breach sealed. On July 1, a second mine was detonated but not followed by an infantry assault.
Throughout the month of June the fearless defenders of Vicksburg suffered under the constant bombardment of enemy guns from reduced rations and exposure to the elements. Reduced in number by sickness and battle casualties, the fort of Vicksburg was spread dangerously thin. Soldiers and citizens alike began to despair that relief would ever come.
At Jackson and Canton General Johnston gathered a relief force which took up the line and marched toward Vicksburg on July 1. By then it was too late as time had expired for the stronghold city on the Mississippi River.