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Conquests in the Old World and the New: Just War?

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When can a polity make a convincing case that it is justified in invading or conquering another state, particularly if the conquering state has not been invaded or attacked by the other?

During the sixteenth century, this question sparked intense debate over the Spanish conquests in the Americas. Within two decades of Columbus’ first Atlantic crossing, Spanish jurists and theologians had become embroiled in what would be a decades-long argument over the nature of the indigenous peoples of the Americas, whether non-Christians could exercise sovereignty, and what right the pope had to dispense lands inhabited by non-Christians to a Christian ruler. The apogee of this argument is usually seen as the so-called Valladolid debate (1550-1551) between Bartolomé de Las Casas and Juan Ginés de Sepúlveda, but the roots of the disagreement over the nature of the Amerindians, and the proper treatment to be accorded them, can be traced back to the first decade of the sixteenth century.

Empire in the Mediterranean

Contemporaneous to the establishment of the first European outposts in the Caribbean, Spanish forces embarked on a series of Old World conquests that included the Kingdom of Naples, a string of North African cities and presidios, and the Kingdom of Navarre.

In the case of Spanish conquests in the Americas, it was the very novelty (to Europeans) of the lands and peoples that inspired the debates over just war, conquest, and empire. By contrast, Spain’s Old World conquests all took place in lands that were anything but novel to fifteenth- and sixteenth-century Spaniards. And yet, these arenas of military engagement also stimulated legal arguments over the criteria to be met for a conflict to qualify as a just war.

The Other Side of Empire examines a series of these justificatory practices as developed in several contexts: against the Christian-ruled lands of Naples and Navarre; against the Muslim-ruled lands of North Africa; and against the Ottoman dynasty, recently ensconced in the former Byzantine capital of Constantinople.

The debates over the American conquests have been well-studied by scholars such as Silvio Zavala, Lewis Hanke, and, more recently, Anthony Pagden. In The Other Side of Empire, my intent is to shed light on a related, but distinct, set of legal arguments composed to justify acts of conquest in the known lands of the eastern hemisphere.

The Political Theology of Early Modern Spanish Monarchy

In the case of the Americas, Spain’s claim to the lands rested (tenuously) on the bulls of “donation” issued by Pope Alexander VI in 1493. It has long been debated whether these bulls were meant to serve as a grant of the western lands, or whether they were merely an exhortation to evangelize.  Regardless, there is consensus that the Spanish claim was predicated on carrying out missionary activity to spread the faith.

Did similar justificatory practices develop to buttress Spanish claims to Mediterranean territories? My findings suggest that the answer is “yes and no.”

In the case of Spanish conquests of lands under non-Christian rule (principally North Africa), claims were rooted in the argument that Spain was engaged in a process of recovery, restoring formerly Christian lands to Christian rule after centuries of Islamic rule. In the case of wars of conquest in Naples and Navarre, Spanish jurists likewise developed rationales for conquest that had a religious basis. But it was distinct from the arguments supporting claims to North Africa. In the case of Spanish arguments opposing French claims to Naples or Navarre, Spanish jurists, theologians, and diplomats asserted that the French were schismatic Christians, that they in fact worked against the common interests of Christendom, and that they posed at least as great a threat to Christian unity as did the Ottomans.

A number of the figures who composed arguments defending Spanish claims to Old World locales were simultaneously drafting treatises supporting Spanish claims in the Americas. These jurists and theologians were in dialogue with one another, and while what they wrote concerning the Americas is relatively well known, there existed an Old World corollary that has been less examined.

The Other Side of Empire reveals the ways Mediterranean geo-politics served as a crucible for the development of legal and moral arguments that undergirded the origins of European colonialism in the Americas.


Andrew W. Devereux is a member of the Department of History at the University of California, San Diego, where he teaches classes on Spanish, Mediterranean, and Environmental history.

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