the struggle of his predecessors with Holy Roman Emperor Louis IV. On 13 April 1346, after protracted negotiations, he excommunicated the Emperor, and directed the election of Charles IV. After the death of Louis in October 1347 Charles received general recognition, ending the schism which had long divided Germany. Clement proclaimed a crusade in 1343, but nothing was accomplished beyond a naval attack on Smyrna on 29 October 1344. He also had a role in the Hungarian invasion of the Kingdom of Naples, which was a papal fief; the contest between Louis I of Hungary and Joanna I of Naples, accused of ordering the assassination of her husband and the former's brother, concluded in 1348 in a trial held in Avignon, at which she was acquitted. Among the other benefits, Clement took advantage of the situation to obtain by her the rights over the city of Avignon. Pope Clement was also involved in disputes with King Edward III of England as a result of the latter's encroachments on ecclesiastical jurisdiction. He also faced problems with the kings of Castile and Aragon. His negotiations for reunion with the Armenians and the Byzantine emperor, John VI Kantakouzenos, turned out to be fruitless. In Italy the Papacy faced a serious challenge to its authority with the commencement of Cola di Rienzo's agitation in Rome. Pope Clement had appointed Cola to a civil position (Senator) at Rome, and, although at first approving of Rienzo's establishment of the tribunate, he later realized the implications of a permanent antagonist to papal government in the form of a popularly elected Tribune, and sent a Papal Legate who excommunicated Rienzo and, with the help of the aristocratic faction, drove him from the city in December 1347. Poland and Bohemia Clement also had warned King Casimir III of Poland, who was already under an interdict laid against him by the bishop of Kraków and the Apostolic See, because he had oppressed the Church of Kraków with intolerable burdens and then harassed the clergy who observed the interdict, that he was attracting more severe penalties to himself. In 1345 Clement sent a nuncio to King Casimir and King John of Bohemia, soliciting them to make peace between themselves, and threatening that, if they rejected his pleas, he would anathematize them and bar them from the sacraments. Responding to numerous complaints against the highhanded behavior of the archbishop of Mainz, Prague's