the papacy's political opponents and those considered heretics. Innocent III proclaimed a crusade against Catharism that failed to suppress the heresy itself but ruined the culture the Languedoc. This set a precedent that was followed in 1212 with pressure exerted on the city of Milan for tolerating Catharism, in 1234 against the Stedinger peasants of north-western Germany, in 1234 and 1241 Hungarian crusades against Bosnian heretics. The historian Norman Housley notes the connection between heterodoxy and anti-papalism in Italy. Indulgence was offered to anti-heretical groups such as the Militia of Jesus Christ and the Order of the Blessed Virgin Mary. Innocent III declared the first political crusade against Frederick II's regent, Markward von Annweiler, and when Frederick later threatened Rome in 1240, Gregory IX used crusading terminology to raise support against him. On Frederick II's death the focus moved to Sicily. In 1263, Pope Urban IV offered crusading indulgences to Charles of Anjou in return for Sicily's conquest. However, these wars had no clear objectives or limitations, making them unsuitable for crusading. The 1281 election of a French pope, MartinIV, brought the power of the papacy behind Charles. Charles's preparations for a crusade against Constantinople were foiled by the Byzantine Emperor Michael VIII Palaiologos, who instigated an uprising called the Sicilian Vespers. Instead, Peter III of Aragon was proclaimed king of Sicily, despite his excommunication and an unsuccessful Aragonese Crusade. Political crusading continued against Venice over Ferrara; Louis IV, King of Germany when he marched to Rome for his imperial coronation; and the free companies of mercenaries. The Latin states established were a fragile patchwork of petty realms threatened by Byzantine successor statesthe Despotate of Epirus, the Empire of Nicaea and the Empire of Trebizond. Thessaloniki fell to Epirus in 1224, and Constantinople to Nicaea in 1261. Achaea and Athens survived under the French after the Treaty of Viterbo. The Venetians endured a long-standing conflict with the Ottoman Empire until the final possessions were lost in the Seventh Ottoman–Venetian War in the 18thcentury. This period of Greek history is known as the Frankokratia or Latinokratia ("Frankish or Latin rule") and designates a period when western European Catholics ruled Orthodox Byzantine Greeks. The threat of the expanding Ottoman Empire prompted further campaigns. In 1389, the Ottomans defeated the Serbs at the Battle of Kosovo, won control of the Balkans from the Danube to the Gulf of Corinth, in 1396 defeated French