The North had not yet completely established her supremacy upon the Mississippi. Two rebel strongholds--Vicksburg and Port Hudson--had successfully resisted Federal attack, and maintained communication between the revolted provinces on either side the great river. The reduction of these was indispensable. General Grant was charged with the important enterprise, and proceeded in February to begin his work. Grant found himself with his army on the wrong side of the city. He was up stream from Vicksburg, and he could not hope to win the place by attacks on that side. Nor could he easily convey his army and siege appliances through the swamps and lakes which stretched away behind the city. It seemed too hazardous to run his transports past the guns of Vicksburg. He attempted to cut a new channel for the river, along which he might convey his army safely. Weeks were spent in the vain attempt, and the country, which had not yet learned to trust in Grant, became impatient of the unproductive toil. Grant, undismayed by the failure of his project, adopted a new and more hopeful scheme. He conveyed his soldiers across to the western bank of the Mississippi, and marched them southward till they were below Vicksburg. There they were ferried across the river; and then they stood within reach of the weakest side of the city. The transports were ordered to run the batteries of Vicksburg and take the chances of that enterprise. When Grant reached the position he sought, he had a difficult task before him. One large army held Vicksburg; another large army was gathering for the relief of the endangered fortress. Soon Grant lay between two armies which, united, greatly outnumbered his. But he had no intention that they should unite. He attacked them in detail, and in every action he was successful. The Confederates were driven back upon the city, which was then closely invested. For six weeks Grant pressed the siege with a fiery energy which allowed no rest to the besieged. General Johnston was not far off, mustering an army for the relief of Vicksburg, and there was not an hour to lose. Grant kept a strict blockade upon the scantily-provisioned city. From his gunboats and from his own lines he maintained an almost ceaseless bombardment. The inhabitants crept into caves in the hill to find shelter from the intolerable fire. They slaughtered their mules for food. They patiently endured the inevitable hardships of their position; and their daily newspaper, printed on scraps of such paper as men cover their walls with, continued to the end to make light of their sufferings, and to breathe defiance against General Grant. But all was vain. On the 4th of July--the anniversary of Independence--Vicksburg was surrendered with her garrison of twenty-three thousand men much enfeebled by hunger and fatigue.