Senior Project Advisor

Diehl, Peter D.

Document Type


Publication Date

Fall 1999


War in the Middle Ages, Christianity and war


War is one of the most gruesome acts in which human society can engage. Therefore, it should be no surprise that almost every culture has found some means of rationalizing its participation in it. Some societies have codified these rationalizations into vast law codes which define how and when the nation may go to war. Other societies, however, had an outlook on war that, although never codified, was yet prevalent throughout the social fabric of that particular society. This attitude towards war is no less stringent than the laws that were written down by other societies. During the Middle Ages, both written and unwritten approaches to war merged through the Germanic migrations into the Roman Empire and the subsequent interactions between the peoples.

From the end of the Roman Empire to the beginning of the Crusades, the relationship between law and war in the Christian Church and in Western Europe underwent significant change. Over time, the pacifism of such writers as Tertullian and Origen would slowly be modified to fit the needs of the time. As Christianity became intertwined with the Empire, the theories changed with it. Pacifism would be seen as an ideal, but as with all ideals there would be a realization that sometimes pacifism could not be the answer. In addition, with the collapse of the Roman Empire, and even a bit before that, the central authority that people expected to come from the Emperor was gone and people were now fighting for expressly regional reasons. With the collapse of the central authority, there was a corresponding reduction in the enforcement of laws, including those pertaining to warfare. Christianity always believed that peace was good, but as time went by it became increasingly obvious that either Christians would have to fight for their existence or be lost to time and anarchy. Soon it became a duty for some Christians to go to war, but only under certain criteria. This might have been overlooked numerous times, but it was still important that Christian Church never stressed wars, but neither did it preach pacifism. Eventually the Church no longer needed to defend itself as much from outside attacks but by that time, it was deeply interwoven with politics. Thus when Europe started to reach beyond itself there were Christians present and through this the Church became embroiled in even more wars.

The Crusades mark a turning point in Western society: no longer was it turned in on itself, but it started to look elsewhere to expand. Although throughout the early Middle Ages there was endemic fighting throughout Europe, there remained some people who read the old works and still sought to understand them, and through these people the theory of war passed. These theories were different from the constant violence of the times and operated as a science with rules both about when a war could start (ius ad bellum) and about how it was to be conducted (ius in' bello). To understand one of the fundamental aspects of the Crusades, the impact of Christianity’s concepts of war, one must look to see how the different ideas of just war slowly melded and changed to legitimize the conquest of another region on religious grounds.



Subjects - Topical (LCSH)

Church history--Middle Ages, 600-1500; Crusades; War--Religious aspects--Christianity; Middle Ages


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