Excerpted from Locomotive by Brian Floca. Copyright 2013 by Brian Floca. Excerpted by permission of Simon & Schuster Children's Publishing. Courtesy of Simon & Schuster Children's Publishing hide caption

itoggle caption Courtesy of Simon & Schuster Children's Publishing

Robert Gates in June 2011 during his final official news conference as secretary of defense. Jason Reed /Reuters/Landov hide caption

itoggle caption Jason Reed /Reuters/Landov