When the United States Army first tried to expand its control into the Southwest before the Civil War, it was an experiment. The desert had often deserted Spanish explorers and so the United States Army tried a different tack. It used camels. This fascinating but unknown part of the development of the Southwest is told in Forrest Bryant Johnson's new book, The Last Camel Charge: The Untold Story of America's Desert Military Experiment. Johnson tells us about that chapter of our history.