The coronation of Stephen V caused a brief constitutional crisis in Hungary, some of the senior king's supporters had left the kingdom and gone into exile to Bohemia, where Ottokar placed them under his protection. It seemed that Joachim was a faithful and reliable supporter of the new monarch. He participated in the royal campaign, when Stephen V launched a plundering raid into Austria (Ottokar's realm) around 21 December 1270. He also fought on the king's side in the spring of 1271, when Ottokar invaded the lands north of the Danube and captured a number of fortresses in Upper Hungary. Joachim resided in the royal camp along the lowland river Dudvág (or Dudváh) in mid-June, then at Pressburg (present-day Bratislava in Slovakia) after Stephen's victory over his enemy. He was a signatory of the two king's agreement in Pressburg on 2 July. Joachim took advantage of his dignity of Ban of Slavonia and his local inherited estates from his father to establish a private territorial domain between the rivers Drava and Sava, in the southwestern part of the kingdom. He acquired or built several castles and their surrounding lordships in the region, for instance Bršljanica (Berstyanóc) and Koprivnica (Kapronca) in Križevci County, and Steničnjak (Sztenicsnyak) in Zagreb County. His distant relative, Hodos Gutkeled administered Zagreb County on behalf of Joachim. Jenő Szűcs emphasized, the neighboring Somogy and Bács counties were also governed by Joachim's brothers Nicholas and Paul, respectively, in the same period, which expanded Joachim's influence over the region – albeit, Zsoldos does not share this view in his archontology. Stephen V and his large companion, including his heir, the 10-year-old Ladislaus and the barons of the royal council, routed to Croatia in the late spring of 1272 to meet his ally and the father-in-law of his son, Charles I of Sicily. The royal march stayed in Zagreb on 26 May, then Topusko on 8 June. They had arrived Bihać (Bihács, present-day in Bosnia and Herzegovina) by 23 June. Two days later, Stephen still issued a royal charter, which reflected that everything went according to plan.