The neighboring Holy Roman Empire under Henry IV invaded Hungary in 1063 to restore Solomon to the throne. Hungary was then ruled by Béla I, whose third daughter Helen was married to Zvonimir. According to Chronicon Pictum, Croatia was also attacked around 1067 by the Carantanian army of Ulric I, who occupied a part of Kvarner and eastern coast of Istria, the "March of Dalmatia". Since the Croatian king was preoccupied with rebellion in Dalmatia, due to the prohibition of Slavic liturgy, Zvonimir was compelled to seek protection from Solomon, King of Hungary instead. Géza I and Solomon helped Zvonimir in restoring authority in the "March of Dalmatia". After they jointly repelled the Carantanians from Croatia, Ban Zvonimir sent gifts to Solomon as a sign of gratitude. Shortly afterwards in 1070 Zvonimir is first mentioned as a Ban of Croatia in charters from Zadar, succeeding Gojko. Croatian charters at the time were issued in the names of both King Peter Krešimir and Ban Zvonimir.