The story of Anton Dilger brings to life a missing chapter in U.S. history and shows, dramatically, that the Great European War was in fact being fought on the home front years before we formally joined it. The doctor who grew anthrax and other bacteria in that rented house was an American -- the son of a Medal of Honor winner who fought at Gettysburg -- on a secret mission, for the German Army in 1915. The Fourth Horseman tells the startling story of that mission led by a brillia...