In the years following America's terrible Civil War, the fate of the U.S. Marine Corps rests in the capable hands of Zachary O'Hara. A first-generation Irish-American and son of a legendary war hero, O'Hara is the one man who can prevent the dissolution of his father's beloved "Wart-Hogs," thereby ensuring his own future as a valuable member of this proud and vital branch of his nation's armed forces.