ROBERT L. O'CONNELL worked as Senior Analyst at the U.S. Army Intelligence Agency's Foreign Science and Technology Center and was a contributing editor to MHQ: The Quarterly Journal of Military History. He is the author of Ghosts of Cannae: Hannibal and the Darkest Hour of the Roman Republic (Random House, 2010), Of Arms and Men: A History of War, Weapons, and Aggression (Oxford, 1989), Soul of the Sword: An Illustrated History of Weaponry and Warfare from Prehistory to the Present (Free Press, 2000).