Negotiating Interfaith Relations in Eastern Christendom: Pope Gregory IX, Bela IV of Hungary, and the Latin Empire

At the beginning of the thirteenth century Pope Innocent III (1198-1216) laid a framework for centralizing papal power over Christian encounters with non-Christians. He enacted legislation to separate Jews from Christians, requiring Jews, for example, to wear distinguishing dress, at the same time that he insisted all should heed his call for their physical safety.¹ He created a definition of orthodoxy that made it possible to identify heresy, called upon bishops to ensure orthodoxy in their jurisdictions, and asserted the rights of popes to replace rulers who refused to comply.² He expanded the scope of crusade targets, developed more ways for the faithful to participate in crusades, and attempted to channel funds for these campaigns through the papacy.³ In every case, Pope Gregory IX (1227-41) not only tried to push forward the programs Innocent had outlined, but also developed new methods to implement them, usually by turning to the mendicant orders. Gregory sought to enforce the legislation over Jews that Innocent had enacted and went further, establishing a campaign against the Talmud, an unprecedented attempt to regulate Jewish belief.⁴ He took the definitions of orthodoxy and means for combating heresy Innocent had created and went further, turning power for ensuring orthodoxy over to mendicant inquisitors who answered directly to him.⁵ He took the structure of central finance and variable targets Innocent had outlined for crusading and went further, using mendicant preachers to consolidate his control over propaganda and using vow redemption, whereby the crusade indulgence could be earned through cash payments rather than fighting in person, to consolidate his control over finance. At the same time, he called for expeditions against schismatics and heretics in Greece, pagans in the Baltic, Muslims in the Iberian peninsula, Mongols in eastern Europe, Stedinger peasants in northern Germany, and political enemies in Italy.⁶ Many historians have found these papal attempts to consolidate control over Christian relations with non-Christians successful, viewing this period variously as the height of papal monarchy, the high point of papal leadership of the crusading movement, or the birth of a persecuting society.⁷

These drives for control came together in December 1235 when Gregory decided that the crusade he had been preaching for the previous year to Jerusalem should instead fight in the Latin empire of Constantinople, then under attack by its two chief enemies, John Vatatzes of Nicaea and John Asen of Bulgaria. One of the primary elements of Gregory's plan was to persuade King Bela IV of Hungary to come to Constantinople's aid. Hungary was a natural place to look for a rapid relief force for Constantinople. Outside of the crusader states themselves, Hungary was the closest Catholic power to the Latin empire.⁸ When Gregory launched his appeal on the empire's behalf, however, his relations with King Bela were poor. The main cause of their conflict was Hungary's non-Christian population. For years Gregory had been pressuring Bela to enforce a stricter separation between Christians and non-Christians in his kingdom. So far Bela had resisted the papal pressure, to his considerable political cost. For Bela, negotiations over support for the Latin empire offered a chance to win concessions from Rome over his treatment of Hungarian minorities. For Gregory, the negotiations posed the question of which threat to Christendom he was more concerned to combat: the internal one presented by Hungarian Jews, Muslims, and "pagans" (mostly Cumans); or the external one presented by the schismatics Vatatzes and Asen. For the modern historian, therefore, the negotiations afford an excellent opportunity to assess one pope's ability to control Christian interactions with non-Christians at the height of papal monarchy.

Modern scholars, most notably Nora Berend, have addressed the conflict between the papacy and Hungarian monarchy over religious minorities in Hungary.⁹ They have not, however, taken Gregory's crusading goals into account. Attending to papal crusading policies is crucial, I argue, because Gregory's crusade priorities caused him to change the demands he made about Hungarian minorities in ways that...