Under the chivalrous rules of warfare as practiced in Europe and the Middle East during the Crusades, enemy aristocrats displayed superficial, and often pompous, respect for one another while freely slaughtering common soldiers. Rather than kill their aristocratic enemy on the battlefield, they preferred to capture him as a hostage whom they could ransom back to his family or country. The Mongols did not share this code. To the contrary, they sought to kill all the aristocrats as quickly as possible in order to prevent future wars against them, and Genghis Khan never accepted enemy aristocrats into his army and rarely into his service in any capacity.