When the tense relationship between Stephen and his father King Béla IV of Hungary sparked into a civil war at the turn of 1264 into 1265, Michael was actively involved in military operations.
Michael suffered a life-threatening injury in the siege, when Stephen led his remaining garrison out of the fort to fight the besiegers, while the duke's rescue army had arrived.
[5] Michael's military career reached its peak in 1268, when the Serbian king Stefan Uroš I invaded the Duchy of Macsó, the southern province of the Kingdom of Hungary, taking advantage of the internal conflict between Béla IV and Stephen.
During the battle, which resulted the decisive victory of the Hungarians, Michael bravely fought and captured two important Serbian barons: an unidentified son-in-law of King Stefan Uroš and a son of the monarch's treasurer in their full armor and with their horses in the sight of Duke Béla of Macsó.
[7] King Béla IV and Queen Maria Laskarina intended to buy the relic from Michael, who thus requested landholdings from the royal couple, instead of an amount of money.
In order to eliminate threat from the Kingdom of Bohemia and to stabilize of the domestic political situation, the newly crowned king reconciled with the former partisans of his late father, including Dominic and Michael Csák.
A few months later, Dominic and Michael temporarily became disgraced due to their involvement in the attack and sack of the Diocese of Veszprém in the spring of 1276, led by their relative Peter Csák.
According to Queen Elizabeth's charter from that year, both of them actively participated in the "horrible attack", therefore she confiscated the village Karos from them and handed over the possession to the bishopric of Veszprém as a compensation.