Martel cemented his place in history with his defense of Christian Europe against a Muslim army at the Battle of Tours in 732. The Iberian Saracens had incorporated Berber light horse cavalry with the heavy Arab cavalry to create a formidable army that had almost never been defeated. Christian European forces, meanwhile, lacked the powerful tool of the stirrup. In this victory, Charles earned the surname "Martel" ("the Hammer"). Edward Gibbon, the historian of Rome and its aftermath, called Charles Martel "the paramount prince of his age".