In the meantime relationships with Urban VI became strained, as he suspected that Charles was plotting against him. In January 1385 he had six cardinals arrested, and one, under torture, revealed Charles' part in a conspiracy. He then excommunicated Charles and his wife, and imposed an interdict over the Kingdom of Naples. The King replied by sending Alberico da Barbiano to besiege the pope in Nocera. After six months of siege, Urban was freed by two Neapolitan barons who had sided with Louis of Anjou, Raimondello Orsini and Tommaso di Sanseverino.