The indignant oligarch pillaged the possessions of the Archdiocese of Esztergom. When the citizens of Kassa (Slovak: "Košice") killed Amade Aba, the powerful oligarch of the north-eastern parts of the kingdom (5 September 1311) Matthew made an alliance with his sons against the king who sided with Kassa. His troops liberated Sáros Castle (Slovak: "Šarišský hrad"), besieged by the king, and then marched against Kassa. At the Battle of Rozgony, the king's armies defeated Matthew's and his allies' troops (15 June 1312). Following the battle, the king occupied the territories of Amade Aba's sons. Although Matthew's domain stayed undisturbed, the occupation of the neighboring territories by the king hindered his expansion.