Hungarians blamed Conrad III for Boris's attack and decided to invade the Holy Roman Empire. Before crossing the river Lajta (now Leitha in Austria), which marked the western border of Hungary, the sixteen-year-old Géza was girded with a sword in token of his coming of age. In the Battle of the Fischa on 11 September, the Hungarian army under the command of Géza and Beloš routed the German troops led by Henry Jasomirgott, Margrave of Austria. Crusaders' march across Hungary (1146–1147) Géza married Euphrosyne, sister of Grand Prince Iziaslav II of Kiev, in the second half of 1146. German–Hungarian relations remained tense as Boris attempted to take advantage of Conrad III's decision to lead a crusade to the Holy Land through Hungary. However Géza, who knew that "he could conquer more easily by gold than by force, poured out much money among the Germans and thus escaped an attack from them," according to the chronicler Odo of Deuil. The German crusaders marched across Hungary without major incident in June 1147. The Illuminated Chronicle relates that some Hungarian noblemen promised Boris "if he could make his way into the kingdom, many would take him for their lord and, deserting the King, would cleave to him." Boris convinced two French noblemen to assist by hiding him among the French crusaders who followed the Germans towards the Holy Land. King Louis VII of France and his crusaders arrived in Hungary in August. Géza learnt that his opponent was with the French and demanded his extradition. Although Louis VII rejected this demand, he held Boris in custody and "took him out of Hungary," according to Odo of Deuil. Having left Hungary, Boris settled in the Byzantine Empire. Active foreign policy (1147–1155) 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,