Once too often in the War Between the States, Great Britain's support for the Confederacy takes it to the brink of war with the Union. The escape of a British-built Confederate ironclad finally ignites the heap of combustible animosities and national interests. When the U.S. Navy seizes it in British waters, the ensuing battle spirals into all-out war. Napoleon III eagerly joins the British and declares war on the United States. Meanwhile, treason uncoils in the North as the anti-war Democrats, known as Copperheads, plot to overthrow the U.S. government and take the Midwest into the Confederacy.