From 1095 until the end of the Middle Ages, western Europeans undertook wars in defence or promotion of their religion throughout the eastern Mediterranean, in the Iberian peninsula, the Baltic, and within Christendom. However, it is the first campaign that is best remembered. ‘Crusades in the eastern Mediterranean’ examines the social, religious, ecclesiastical, and political context of this first expedition and the ones that followed. Generations that followed have been amazed by the exploits of the armies and fleets from Western Europe during this time. Western intellectuals have justified it using the language of theology.