Between 1815-1860, the tiny American army took on many new and often daunting tasks. In the face of civil opposition to the very existence of a professional military, the first battle officers and supporters had to win after 1815 was that of simply preserving some small professional force. As American interests expanded further west and conflict with Native Americans increased, the army was charged with the dual responsibility of peacekeeper and conqueror. Its most dramatic successes, however, came during the Mexican War and the conquest of the American Southwest. Against this back drop,...