April 12, 1861. With one jerk of a lanyard, one shell arching into the sky, years of tension explode into civil war. And for those men who do not know in which direction their loyalty calls them, it is a time for decisions. Such a one is Lieutenant Samuel Bowater, an officer of the U.S. Navy and a native of Charleston, South Carolina. Hard-pressed to abandon the oath he swore to the United States, but unable to fight against his home state, Bowater accepts a commission in the nascent Confederate Navy, where captains who once strode the quarterdecks of the world's most powerful ships are now assuming command of paddle wheelers and towboats. Taking charge of the armed tugboat Cape Fear, and then the ironclad Yazoo River, Bowater and his men, against overwhelming odds, engage in the waterborne fight for Southern independence

Having survived the bloody Battle of New Orleans and the loss of their ironclad Yazoo River, captain Samuel Bowater, engineer Hieronymus Taylor, and the survivors of their crew are given new orders – take command of an ironclad warship being built in Memphis, Tennessee.Bowater and his men take passage upriver from "Mississippi" Mike Sullivan, one of the wild, undisciplined captains of the River Defense Squadron, only to find, on their arrival, that their ship is not even half built and the enemy is closing fast. Against their better judgment, Bowater and crew join forces with the mercurial Sullivan on board his ad hoc river gunship the General Page. Outnumbered and outgunned, the Confederates once again fling themselves bravely at the overwhelming power of the Yankee invaders. The deadly back-and-forth fight along the Mississippi ends at last in the massive naval battle of Memphis, and the near-suicidal attempt by the Confederates to hold back the Northern flood