Confederate Gen. P.G.T. Beauregard was sitting down to breakfast in the Virginia house of Wilmer McLean in 1861 when a cannonball burst into the room via the chimney. The destruction of the fireplace ruined the morning meal. Beauregard was using McLean's house as his headquarters for the First Battle of Bull Run. Three months had passed since the Confederate shelled Fort Sumter, South Carolina, and booted the Union garrison out of the state. The Federal army was making a play for the...