The leading First Corps of the Army of the Potomac camps four miles west of Gettysburg

After days of hard marching to find and intercept the Army of Northern Virginia's invasion of Pennsylvania, the lead Corps of the Army of the Potomac, under its popular General John F. Reynolds, had reached within four miles of Gettysburg. Eleven and Twelve Corps were encamped just six miles further back. Confederate forces were planning to concentrate there and the next day advance elements of the two great armies made contact on the outskirts of the town and the pivotal battle began. (By John Osborne)