Less than a week after the disastrous Union defeat at Fredericksburg, Virginia, on December 13, 1862, Abraham Lincoln confronted one of the most serious political crises he faced during the war. The debacle fed mounting frustration among Republicans over the administration’s conduct of the war. Led by its Radical members, the Senate Republican caucus tried to force Secretary of State William H. Seward out of the Cabinet. The Radicals accused Seward of opposing vigorous prosecution of the...