The novel starts out when Harrison, a Confederate spy, reports to James Longstreet that 80,000 to 100,000 Union soldiers have marched within 200 miles of Lee's position near Chambersburg, Pennsylvania. Harrison also bears news of a change in Union leadership. Major General George Meade had replaced "Fighting Joe" Hooker as commander of the Union Army. Lee sees this change as an opportunity to strike while the new commander gets his bearings. He decides to concentrate on Gettysburg, the small town where several roads in the area converge, where he intends to cut the Union army off from…