The Battle of Gettysburg, fought from July 1 to July 3, 1863, is considered the most important engagement of the Civil War. After a great victory over Union forces at Chancellorsville, General Robert E. Lee marched his Army of Northern Virginia into Pennsylvania in late June 1863. On July 1, the advancing Confederates clashed with the Union’s Army of the Potomac, commanded by General George G. Meade, at the crossroads town of Gettysburg. The next day saw even heavier fighting, as the Confederates attacked the Federals on both left and right. On July 3, Lee ordered an attack by fewer than 15,000 troops on the enemy’s center at Cemetery Ridge. The assault, known as “Pickett’s Charge,” managed to pierce the Union lines but eventually failed, at the cost of thousands of rebel casualties, and Lee was forced to withdraw his battered army toward Virginia on July 4. Its futility was predicted by the charge's commander, Lt. Gen. James Longstreet, and it was arguably an avoidable mistake from which the Southern war effort never fully recovered militarily or psychologically. The farthest point reached by the attack has been referred to as the high-water mark of the Confederacy.