Emperor Charles IV and Rudolf IV of Austria signed a treaty of alliance against the patriarch of Aquileia, who was Louis's ally, in August 1361. Fearing the formation of a coalition along the western borders of Hungary, Louis asked his former enemy, Louis of Taranto (Joanna I's husband), to send at least one of his brothers to Buda, and mediated a reconciliation between Rudolph IV and the patriarch. At a meeting with Louis's envoys in Prague, Emperor Charles made an insulting remark about Louis's mother, stating that she "was shameless", according to Jan Długosz's chronicle. Louis demanded an apology, but the emperor did not answer.