Although outnumbered, Lee divided his force, leaving a small holding force at Fredericksburg and leading the majority of his men through the Wilderness, blocking hooker at the Chancellorsville crossroads. The next day, General Stonewall Jackson was sent to flank the Union right. This had devastating results, as the Union XI corps was routed. The third day of fighting was the fiercest, as Lee launched several assaults on the Union position (who at this point were on the defensive). The next day, Hooker ordered a withdraw from the battlefield due to heavy casualties.
Chancellorsville would come to have a great impact on the way the war turned out. After the victory, Lee was free to plan an invasion of the North, which would ultimately result in the battle of Gettysburg. Many historians also view the battle as the finest display of tactics that Lee exhibited during the entire war.
The same ground, and then some, that the battle of Chancellorsville would be scenes for the Battle of the Wilderness, which took place in 1864. Many entries created for Clio that focus on these two battles will seem to overlap, so be careful not to confuse them all as one big battle.