For almost a century the defense of the frontier was the chief consideration in the military policy of the United States, " Dr. Wesley observes. His book is the first detailed historical study of the military policy of the United States in the years immediately following the War of 1812, the period during which its policy was becoming clearly defined. The political, military, and economic factors lying behind the establishment of that policy are all given thorough treatment by the author, who discusses the various methods of defense evolved against the British to the north, the Spaniards in the south and west, and the Indians everywhere. The author demonstrates the importance of Indian affairs, of the factory system, and of the fur trade as elements in the westward expansion of the United States.