Disputes among European powers led to the formation of two coalitions in the late 1140s. One alliance was formed by the Byzantine Emperor Manuel I Komnenos and Conrad III against Roger II of Sicily who had invaded Byzantine territories. Géza sided with Roger II and his allies, including the rebellious German prince, Welf VI and Uroš II of Serbia. Géza sent reinforcements to his brother-in-law, Grand Prince Iziaslav II, against Prince Vladimir of Chernigov in the spring of 1148. The Grand Principality of Serbia rebelled in 1149, forcing Emperor Manuel I to interrupt his preparations for an invasion of Southern Italy and invade Serbia in 1149. According to the emperor's panegyrist Theodore Prodromus, Hungarian forces supported the Serbs during the emperor's campaign. The Hypatian Codex says that Géza referred to his war against Emperor Manuel when excusing himself for refusing to send reinforcements to Iziaslav II whom Yuri Dolgorukiy, Prince of Suzdal, expelled from Kiev in August 1149. Hungarian auxiliaries supported Iziaslav II to reoccupy Kiev in the early spring of 1150, but before long Yuri Dolgorukiy expelled Iziaslav from the town. In autumn, Géza led his army against Volodimirko of Halych, who was Yuri Dolgorukiy's close ally. He captured Sanok, but Volodimirko bribed the Hungarian commanders, who persuaded Géza to leave Halych before November.