The greatest threat to Byzantium was not the Muslims but their Christian counterparts in the West — Michael VIII knew that the Venetians and the Franks would no doubt launch another attempt to establish Latin rule in Constantinople. The situation became worse when Charles I of Anjou conquered Sicily from the Hohenstaufens in 1266. In 1267, Pope Clement IV arranged a pact, whereby Charles would receive land in the East in return for assisting a new military expedition to Constantinople. A delay on Charles' end meant that Michael VIII was given enough time to negotiate a union between the Church of Rome and that of Constantinople in 1274, thus removing papal support for an invasion of Constantinople.