 Complete the following phrase:  During the early years of his episcopate, the oligarch Amadeus Aba ruled de facto independently the northern and north-eastern counties of the kingdom, including the overwhelming territory of the Diocese of Eger. Amadeus was considered a strong mainstay of Charles during the war of succession to the Hungarian throne, and Martin maintained a good and cooperative relationship with the oligarch. For instance, Martin and six canons resided in the fort of Gönc, Amadeus provincial seat in 1307. Unlike in the case of other oligarchs during the era of feudal anarchy, there is no source that Amadeus Aba has materially and in rights harmed the property and institutions of the Church in his province. The political situation changed drastically when Amadeus Aba was killed during a skirmish with the burghers of Kassa today Košice, Slovakia in September 1311. The king saw an opportunity to liquidate one of the most extensive oligarchic provinces without hindrance. Charles entrusted Martin and sent his two envoys, Archbishop Thomas of Esztergom and Bishop Stephen Kéki of Veszprém to the province in October 1311, where the three judges arbitrated an agreement between Amadeus widow and sons and the town, which also prescribed that the Abas withdraw from two counties and allow the noblemen inhabiting their domains to freely join Charles. However, the Aba clan did not accept political downgrading and soon entered into an alliance with Charles most ardent enemy, Matthew Csák against the king. Alongside other lords and prelates, Martin participated with his banderium in the royal campaign, which consisted of successful sieges and the decisive 