Vicksburg had just fallen to Union forces. The Confederates were trapped north of the Potomac River after their defeat at Gettysburg. And after two years of civil war and battlefield calamity, Abraham Lincoln thought he saw the glimmer of victory.

On July 7, 1863, three days after Vicksburg's surrender and four days after Gettysburg, Lincoln took out a sheet of blue-lined paper and wrote to his general in chief, urging that the fleeing rebels be destroyed. If they were, Lincoln wrote, "the rebellion will be over."