When there was a battle to be fought, these warriors were there: gladiators, conquistadors, ninjas, Vikings . . . From Roman arenas to the lawless high seas, this series for readers age 12 and up spotlights the world's most fearsome combatants. Each title surveys the history of a fighting group, examining key leaders, weapons, skills, rules of warfare, and reasons for existing. As the Age of Discovery began and the number of ships crossing the oceans...