On the eve of their conflict, which caused a civil war lasting until 1266, Nicholas and Joachim were considered supporters of the monarch. Joachim served as cup-bearer in the ducal court of the child Béla, Duke of Slavonia, King Béla's favored son in 1263. According to historians László Zolnay and Jenő Szűcs, the Gutkeled brothers left Béla's allegiance and joined the partisans of Duke Stephen in early 1264, not long before the outbreak of the civil war. As a result, Joachim was granted the lordships of Hațeg, Miháld and Jeszenő (present-day Hațeg, Mehadia in Romania and Jasenov in Slovakia, respectively), which all laid in the eastern parts of the Kingdom of Hungary, governed by Duke Stephen after the division of the realm in 1262. In contrast, historian Attila Zsoldos doubts his colleagues' theory, considering there is no clear evidence of that, as Joachim had no prominent – if any – role in the subsequent civil war due to his relatively young age, and may have received the large estates later, after Stephen's ascension to the Hungarian throne in 1270. Joachim married Ruthenian princess Maria Romanovna in the second half of the 1260s. She was the daughter of Roman Danylovich, Prince of Navahrudak and Gertrude von Babenberg (the general heiress of her family), who were married with King Béla's mediation in 1250, after he met and concluded a peace treaty with Roman's father, Daniil Romanovich, Prince of Halych. With this marriage, Joachim Gutkeled became a relative of three royal dynasties – the Árpáds, the Babenbergs, which were extinct on the male branch by then, and the Rurikids. The couple produced only a daughter, leaving Joachim without male descendants. Their unnamed daughter married Roland Borsa, who served as Voivode of Transylvania in 1282 and from 1284 to 1294. Her daughters' quarter was paid by Paul Gutkeled's sons in 1322. She was still alive in 1337. Béla IV died on 3 May 1270. Stephen arrived to Buda within days and nominated his own partisans to the highest offices. On this occasion, Joachim Gutkeled was made Ban of Slavonia, replacing the late Béla's prominent partisan, Henry Kőszegi.