WORLD HISTORY: C 500 TO C 1500. When George Bush inaugurated the War on Terror in 2001, he referred to it as a crusade. A medieval Crusade could be defined thus: a holy war initiated by the Pope on God's behalf in which the participants took the cross and received remission for their sins. The First Crusade, launched in 1095, ushered in a period of almost 200 years of Christian rule in the Levant, yet over time crusades were directed against a variety of opponents, not just Muslims in the Middle East: against Cathar heretics, political enemies of the papacy, the Mongols, pagan tribes of northern Europe, and the Ottoman Turks, well into the sixteenth century. As Jonathan Phillips demonstrates in this timely and revealing study, crusading has proven to be a remarkably adaptable and long-lasting phenomenon, embedded in the actions and consciousness of the West for centuries.