Medieval Geopolitics: War in the Medieval Mind

By Andrew Latham

How was war understood in late medieval culture? Or, put slightly differently, how was organized violence conceptualized in the political imagination of late medieval Latin Christendom?

In order to address these questions, it is useful to look to the works of St. Augustine and St. Thomas Aquinas; for, in this context as in others, these works expressed, shaped and defined the basic contours of late medieval political culture.  What, then, were the views of these scholars?

On the one hand, Augustine viewed war as a consequence of humanity’s fallen nature. In pre-lapsarian times, human society was well ordered and peaceful; all humans were naturally subject to what Augustine calls the “bonds of peace” and contention was absent.  In these circumstances, there was neither the need for a coercive state to guide human activity nor the “contestation by force” which results from the disordered pursuit of selfish ends.

With the fall of humanity and its division into the Two Cities, however, war was decisively introduced into human affairs. This occurred because citizens of the Earthly City, distinguished from those of the Heavenly City by their lust for material goods and for domination over others, discovered that they could use individual and collective violence to further their selfish ends. They could, in a word, successfully pursue their unjust and vicious goals through war. Augustine thus fundamentally understood war to be a consequence of sin – that is, of humanity’s rebellion against God and its selfish pursuit of its own sinful ends. Perhaps not surprisingly, as a kind of corollary to this he also viewed war as a more common state of affairs than peace.  Indeed, Augustine believed that war was the natural and normal state into which fallen humanity had descended; peace, when it broke out, was little more than an interlude between ongoing bouts of violent conflict and contestation.

But if Augustine undeniably viewed war as a consequence of the Fall he also saw it as a punishment and remedy for sin. With respect to war as a punishment for sin, Augustine argued that the pain, suffering and loss that war inevitably brings in its wake is just reward for the Earthly City’s rebellious disposition toward God and the inherent immorality of its citizens. Regarding war as a remedy for sin, Augustine argued that it was a means of chastising the immoral and rebellious and thus of compelling then to act righteously. As he himself put it:

“For God’s providence constantly uses war to correct and chasten the corrupt morals of mankind, as it also uses such afflictions to train men in a righteous and laudable way of life, removing to a better state those whose life is approved, or else keeping them in this world for further service.”

For Augustine, then, war was a means of scourging sinners and of moving them toward repentance and reformation. In the event that it did not bring about such a change of heart, however, it could nevertheless serve the lesser, but non-trivial goal, of subduing the unjust and restraining them from perpetrating their immoral acts.

Saint Augustine by
Giacinto Gimignani (1606–1681)

On a different plane, Augustine also saw war as an instrument for achieving the common “intermediate goods” that the state provided to the citizens of both the Earthly and Heavenly Cities: peace, concord, “the satisfaction of material needs, security from attack and orderly social intercourse”.  Augustine, it will be recalled, rejected the notion that the state could serve the “common good” in the Ciceronian or Aristotelian sense of promoting the good life, virtue or perfection.  All that was possible, he argued, was a qualified agreement between the citizens of the Two Cities on limited number of intermediate goods that had a “common usefulness” (communis utilitas).

Accordingly, for Augustine the moral purpose of the state was merely “to safeguard security and sufficiency (securitatem et sufficientam vitae)”. Against this backdrop, war provided another, qualitatively different, type of remedy for the consequences of the Fall: it was an instrument both for defending the (imperfect but still morally defensible) state against external attack and for restoring what Augustine called “earthly peace”.  As security and earthly peace were conducive to the Christian pursuit of fuller communion with God, he considered wars fought for these purposes to be not only lawful, but at times a “stern necessity”.

Just and unjust wars

It is worth emphasizing at this point that Augustine made a clear distinction, no doubt grounded in the legal and political realities of the era in which he lived, between private violence and public war.  The former, he argued, entailed private individuals using force to advance private interests.  To him, such violence was both sinful and illicit, even if committed in self-defense.  The latter, on the other hand, entailed legitimate public authorities using force to defend the community and its legitimate rights and interests.  As such it was inherently just and lawful.  Indeed, according to Augustine the legitimate civil ruler not only has the authority to wage war on behalf of the political community, but the positive moral obligation to do so. Failure to wage war in defense of the community would be an abrogation of the ruler’s responsibility both to his compatriots and to God.

Finally, and to some extent pulling all this together, Augustine made a clear ontological distinction between just and unjust wars – a distinction that was to persist through the late Middle Ages and, in a slightly modified and secularized form, into the late modern era.  The impulse behind drawing this distinction derived primarily from the desire to provide Christians, who had little chance of insulating themselves from the ubiquitous conflicts of the Earthly City, with some guidance regarding how to judge and justify war.  After refuting arguments in favor of pacifism, Augustine drew on the works of Cicero and St. Ambrose to develop the argument that wars were just and licit – and therefore worthy of the support of Christian kings and their subjects – if and only if they met certain criteria.  First, he argued, a just war must be declared by a competent and legitimate authority, by which he meant kings and emperors acting on behalf of a political community.

Second, he argued, to be considered just, a war must have a just cause such as defending the state from external aggression; avenging injuries against the state; punishing another state for failing to redress injuries perpetrated by its citizens; restoring illicitly seized property to its rightful owner; and defending the Church against heresy.  And third, Augustine argued that a just war was one prosecuted with right intent – that is, with an inward disposition toward restoring peace rather than conquering territory or subjugating people; and toward acting out of Christian love rather than hatred, greed, pride or the will to dominate.  Unjust wars, Augustine argued, were those that failed to meet one or more of these standards.

Later medieval understandings of the nature and purpose of war were deeply rooted in, and powerfully conditioned by, this Augustinian perspective.  But the understanding of war particular to this era also had an important Aristotelian dimension, expressed most systematically in the works of St. Thomas Aquinas and his continuators Peter of Auvergne and Ptolemy of Lucca. Drawing heavily on the recently re-introduced works of Aristotle, but also on the works of Augustine himself, these scholars largely accepted the Augustinian argument that the roots of war lay in humanity’s Fall.

Public war and private violence

But whereas Augustine saw war as a punishment and remedy for sin, or at best a means of defending a state which was itself a punishment and remedy for sin, Aquinas and his circle characteristically saw it as a necessary and legitimate means of securing the morally more positive Aristotelian political community.  For them, the common good served by war was related to the goal of creating and securing a political community that enabled its citizens to lead a truly ethical life – the “good life” – ordered to the fulfillment of humanity’s distinctive capacity both to reason (i.e. to be rational) and to live life according to the dictates of reason (i.e. to live a life of virtue or moral excellence).  In the unjust and imperfect world of fallen humanity, this sometimes required the use of force to defend the community, restore peace or punish wrongdoers.

14th century depiction of Thomas Aquinas

The Thomists’ ultimate contribution was to inject the Aristotelian notions of the common good, rather than the more limited Augustinian concept of common utility, into the late medieval ontology of war.  While they largely accepted the Augustinian criteria for just war, they thus re-grounded just cause in Aristotelian political science.  In a similar way, they also re-grounded the prince’s war-making authority in Aristotelian terms, arguing that it derived not so much from God (as Augustine had argued) as from the king’s role as guardian (tutor) of the kingdom.

Beyond this, Aquinas also clearly articulated the difference between war and other forms of politics and violence.  In the Summa Theologica he put it thus:

“War, properly speaking, is against an external enemy, one nation as it were against another, and brawls are between individuals, one against one or a few against at few.  Sedition in its proper sense is between mutually dissident section of the same people, when, for example one part of the city rebels against another.”

On this view, which historian Philippe Contamine argues is representative of late medieval thought, feuds and other forms of private war are not, properly speaking, war at all, but fell into an altogether different class or order of violence.

To the extent that these two traditions defined the horizons of the late medieval political imagination, they effectively worked together to embed and naturalize an understanding of war comprising the following beliefs: war was a natural and inevitable (if lamentable) aspect of the human condition; war was an instrument of the state necessary to secure peace and order; and war was a legitimate means of pursuing rights and promoting justice. This understanding also emphasized the categorical differences between public war on the one hand and various forms of private violence on the other.  While some might emphasize the Augustinian strain and others the Thomist, few would have understood the nature of public war in terms other than these.

Andrew Latham is a professor of political science at Macalester College in Saint Paul, Minnesota. He is the author, most recently, of The Idea of Sovereignty At the Turn of the 14th Century. You can visit Andrew’s website at or follow Andrew on Twitter @aalatham 

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Top Image: UBL Cod. Perizoni F.17 Leiden I Maccabees  fol. 015v

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