kind of misery had been endured till it could be borne no longer, Vicksburg was surrendered on July 4. [Illustration: The Vicksburg Campaign] Five days later (July 9, 1863), Port Hudson surrendered, and the Mississippi, as Lincoln said, "flowed unvexed to the sea." It was open from its source to its mouth, and the Confederacy was cut in two. %444. Driving the Confederates eastward; Chickamauga and Chattanooga%.--While Grant was besieging Vicksburg, Rosecrans by skillful work forced Bragg to retreat from his position south of Murfreesboro; then in a second campaign he forced Bragg to leave Chattanooga and retire into northwestern Georgia. Bragg here received more troops, and attacked Rosecrans in the Chickamauga valley (September 19 and 20, 1863), where was fought one of the most desperate battles of the war. So fierce was the onset of the Confederates that the Union right wing was driven from the field. But the left wing, under General George H. Thomas, a grand character and a splendid officer, by some of the best fighting ever seen held the enemy in check and saved the army from rout. By his firmness Thomas won the name of "the Rock of Chickamauga." Rosecrans now went back to Chattanooga. Bragg followed, and taking position on the hills and mountains which surround the town on the east and south, shut in the Union army and besieged it. For a time it seemed in danger of starvation. But Hooker was sent from Virginia with more troops; the Army of the Tennessee under Sherman was summoned from Vicksburg; Rosecrans was superseded by Thomas, and Grant was put in command of all. Then matters changed. The forces under Thomas, moving from their lines, seized some low hills at the foot of Missionary Ridge, east of Chattanooga (November 23). On the 24th, Hooker carried the Confederate works on Lookout Mountain, southwest of the city, in a conflict often called the "Battle above the Clouds"; and Sherman was sent against the northern end of Missionary Ridge, but succeeded only in taking an outlying hill. On the 25th Sherman renewed his attack, but failed to gain the main crest, whereupon Thomas attacked the Ridge in front of Chattanooga, carried the heights, and drove off the enemy. Bragg retreated to Dalton, in northwestern Georgia, where the command of his army was given to Joseph E. Johnston. %445. "Marching through Georgia"; "From Atlanta to the Sea."%--As the Confederates had thus been driven from the Mississippi River, and forced back to the mountains, they had but two centers of power left. The one was the army under Lee, which, since the defeat at Gettysburg, had been lying quietly behind the Rapidan and Rappahannock rivers, protecting Richmond. The other was the army at Dalton, Ga., now under J. E. Johnston. [Illustration: WAR FOR THE UNION Breaking the Confederate Line]