In October General John C. Pemberton, a Philadelphian by birth, succeeded Van Dorn in command of the Confederate forces at Vicksburg. General Grant planned to divide the army of the Tennessee, Sherman taking part of it from Memphis down the Mississippi on transports while he would move overland with the rest of the army and coöperate with Sherman before Vicksburg. But the whole plan proved a failure, through the energies of Van Dorn and others of the Confederate army in destroying the Federal lines of communication. Sherman, however, with an army of about 32,000 men, left Memphis on December 20th, and landed a few days later some miles above Vicksburg, and on the 29th made a daring attack on the Confederate lines at Chickasaw Bayou, and suffered a decisive repulse with a loss of 2,000 men. Sherman now found the northern pathway to Vicksburg impassable and withdrew his men to the river, and, to make up triple disaster to the Federals, General Nathan Forest, one of the brilliant Confederate cavalry leaders, with 2,500 horsemen, dashed through the country west of Grant's army, tore up many miles of railroad and destroyed all telegraph lines and thus cut off all communication of the Federals. In the meantime General Van Dorn pounced upon Holly Springs, capturing the guard of 1,500 men and burning Grant's great store of supplies, estimated to be worth a million and a half dollars, thus leaving Grant without supplies, and for many days without communication with the outside world. It was not until about the middle of January that he heard, through Washington, of the defeat of Sherman at Chickasaw Bayou. Grant changed his plan of attack and decided to move his army below Vicksburg and approach the city from the south. Another plan was to cut a channel through the peninsula opposite Vicksburg and again try the project of changing the bed of the Mississippi so as to leave Vicksburg some miles inland. For six weeks thousands of men worked on this ditch; early in March the river began to rise and on the morning of the 8th it broke through the embankments and the men had to run for their lives. Many horses were drowned and great numbers of implements submerged. The "Father of waters" had put a decisive veto on the project, and the same was abandoned. On the night of April 16th Porter ran past the batteries of Vicksburg with his fleet after days of preparation. They left their station near the mouth of the Yazoo about nine o'clock. Suddenly the flash of musketry fire pierced the darkness. A storm of shot and shell was rained upon the passing vessels. The water of the river was lashed into foam by the shot and shell from the batteries. The gunboats answered with their cannon. The air was filled with flying missiles. The transport, Henry Clay, caught fire and burned to the water's edge. By three in the morning the fleet was below the city and ready to coöperate with Grant's army.