From Fort Snelling on the upper Mississippi and Fort Leavenworth on the Missouri to Fort St. Philip below New Orleans, the string of military bases along the western frontier of the United States played an essential part in the orderly advance of settlement following the War of 1812. Small, isolated, and insignificant in terms of fortification-after all, the authorized strength of the whole army was only 6,000 men-they were nevertheless the stabilizing and moderating force in the dramatic "rise of the new West." For twenty years prior to the Mexican War, Colonel George Croghan, as inspector...