One was called "a tin can on a shingle"; the other, "a half-submerged crocodile." Yet, on a March day in 1862 in Hampton Roads, Virginia, after a five-hour duel, the U.S.S. Monitor and the C.S.S. Virginia (formerly the U.S.S. Merrimack) were to change the course of not only the Civil War but also naval warfare forever. Using letters, diaries, and memoirs of men who lived through the epic battle of the Monitor and the Merrimack and of those who witnessed...