In the summer of 1863, Confederate Gen. Robert E. Lee launched his second invasion of Northern territory. Like his last foray that ended at bloody Antietam, Lee sought to score politically meaningful victories, take the war out of the ravaged Virginia farmland, and gather supplies for his army. He was pursued first by Union Gen. Joseph Hooker, and then by Gen. George Meade, who replaced Hooker in late June. The opposing forces collided at Gettysburg, Pennsylvania, on July 1. In severe fighting, the Confederates swept the Federals from the fields west and north of town, but were unable to secure the heights to the south. The following day, Lee attacked the Federals on the heights, but failed to dislodge the defenders. On July 3rd, Lee attacked the Union center on Cemetery Ridge and was repulsed in what is now known as Pickett’s Charge. Lee's second invasion of the North had failed, and had resulted in heavy casualties; an estimated 51,000 soldiers were killed, wounded, captured, or listed as missing after Gettysburg.