Waldemar Heckel is a Canadian historian. Internationally regarded as a researcher on Alexander the Great and his times, he has published numerous articles and books on related subjects, including The Conquests of Alexander the Great and The Marshals of Alexander's Empire. Until his retirement in late 2013, he taught as a professor of ancient history at the University of Calgary.Peter Tsouras is a retired analyst of military all-source intelligence for the U.S. Government (National Ground Intelligence Center and the Defense Intelligence Agency). He is also a retired Lieutenant Colonel in the U.S. Army Reserve and has written 30 books on military history and alternate military history as a military historian and biographer.