The Battle of Gettysburg lasted 3 days. General George G. Meade met Lee's army and the Confederates pushed the Union to Cemetery Ridge. Lee sent George E. Pickett who had 15,000 men to lead an assault on the ridge. Pickett's Charge left many dead. Only 100 men made it to the top of the ridge where they held their position for a short time.
General Lee was forced to retreat. 7,000 men were killed, 44,000 wounded. http://newspaper.li/gettysburg/