The Battle of Gettysburg was fought because General Lee had a need to find food and other supplies for his men who had just been through a very hard winter. The Battle of Gettysburg was the most famous of all battles during the Civil War, and it involved the greatest number of fatalities in the entire war.
The small town of Gettysburg was a young developing town that had a system of ten roads leading into town. This brought General Lee and his army into the town. The battle was often seen as the turning point in the war because once Lee and his army were defeated and the Confederate army retreated, they were never able to recover.