On January 1, Lincoln issued the Emancipation Proclamation, which followed a preliminary proclamation made on September 22, 1862. The proclamation declared that all slaves held in territory controlled by the Confederates were henceforth free. It did not actually free any slaves, but made the abolition of slavery an issue of the war. This had an important effect on world opinion.
General Joseph Hooker succeeded Burnside in command of the Army of the Potomac and in May launched an offensive with heavy numerical superiority. Again Lee and Jackson were better in maneuver, and Hooker was badly defeated at the Battle of Chancellorsville (May 24). However, during the battle, Jackson was accidentally shot and mortally wounded by his own troops, depriving the Confederacy of one of its ablest generals.Union soldiers engage confederate troops.
In late June, Lee again invaded the north. Before the armies made contact, Hooker was replaced by General George G. Meade. At Gettysburg, Pennsylvania, during the first three days of July, the armies met in the bloodiest battle ever fought in the Western Hemisphere. On July 3, Lee risked everything in an direct assault on the Union center. The attack, called Pickett's Charge, was repelled by withering artillery volleys. The failure of Pickett's Charge was a crucial turning point in the war, and the assault's point of farthest advance is sometimes called the High Water Mark of the Confederacy. After their defeat, Lee's men retreated into Virginia, and the armies maneuvered indecisively for the rest of the year.
In the west, Grant began operations against Vicksburg. The capture of this city would open the Mississippi River to Union transportation, and cut off Louisiana, Arkansas, and Texas from the rest of the Confederacy. In May, Grant marched his army down the west bank of the river to a point below Vicksburg. Here Flag Officer David D. Porter, who had led his river fleet past Vicksburg at night, ferried the army to the east bank. In five sharp battles, Grant prevented Johnston from reinforcing Vicksburg's defenders, and drove General John C. Pemberton into the city, which was then besieged. On July 4, the day after Gettysburg, Pemberton surrendered his starving army to Grant. Four days later, Port Hudson surrendered to General Nathaniel P. Banks. Lincoln said, The Father of Waters again goes unvexed to the sea.
From the beginning of 1863, Rosecrans and Bragg had faced each other between Murfreesboro and Chattanooga. In late June, Rosecrans executed a series of skillful flanking movements that maneuvered Bragg out of Chattanooga. While Rosecrans was in pursuit, General James Longstreet arrived to aid Bragg with a corps from Lee's Army of Northern Virginia. Rosecrans was trapped and badly defeated at Chickamauga, Georgia (September 1920). Only the stand of General George H. Thomasthereafter called The Rock of Chickamaugasaved Rosecrans' army from complete rout. His army then moved to Chattanooga, where it was besieged by the Confederates.
In October, Grant was given command of the Military Division of the Mississippi, and Thomas replaced Rosecrans. Grant's first move was to open a supply line into Chattanooga so his starving troops could be fed. He then planned a full-scale battle to raise the siege. Hooker, with a corps from the Army of the Potomac, captured Lookout Mountain on November 24. The next day, General William T. Sherman, commanding the Army of the Tennessee, attacked the Confederate right flank. Thomas, commanding the Army of the Cumberland, was ordered to make a diversionary attack in the center. Instead, his troops charged up Missionary Ridge and scattered Bragg's main forces into nearby Georgia. They were reassembled at Dalton, and Joseph E. Johnston replaced Bragg.