With their origins as blood rites staged at the funerals of rich aristocrats, gladiatorial combat is one of the defining images of ancient Rome. For more than 600 years, people flocked to arenas to watch these highly trained warriors participate in a blood-soaked spectacle that was part sport, part theatre and part cold-blooded murder. Gladiatorial contests were a spectacular dramatization of the Roman emperor's formidable power. Gladiator...