Saxon overlordship, Wenceslaus's father Vratislaus had forged an alliance with the Bavarian duke Arnulf, a fierce opponent of King Henry at that time. The alliance became worthless, however, when Arnulf and Henry reconciled at Regensburg in 921. Early in 929, the joint forces of Duke Arnulf of Bavaria and King Henry I the Fowler reached Prague in a sudden attack that forced Wenceslaus to resume the payment of a tribute first imposed by the East Frankish king Arnulf of Carinthia in 895. Henry had been forced to pay a huge tribute to the Magyars in 926 and needed the Bohemian tribute, which Wenceslaus probably refused to pay after the reconciliation between Arnulf and Henry. Another possible reason for the attack was the formation of the anti-Saxon alliance between Bohemia, the Polabian Slavs, and the Magyars. Wenceslaus introduced German priests into his realm and favoured the Latin rite instead of the old Slavic, which had gone into disuse in many places for want of priests. He also founded a rotunda consecrated to St. Vitus at Prague Castle in Prague that was the basis of present-day St. Vitus Cathedral. Assassination In September 935, a group of nobles allied with Wenceslaus's younger brother Boleslav plotted to kill him. After Boleslav invited Wenceslaus to a celebration of the feast of Saints Cosmas and Damian in Stará Boleslav, three of Boleslav's companions (Tira, Česta, and Hněvsa) fell on the duke and stabbed him to death. As the duke fell, Boleslav ran him through with a lance. According to Cosmas of Prague, in his Chronica Boëmorum of the early 12th century, one of Boleslav's sons was born on the day of Wenceslaus's death. Because of the ominous circumstance of his birth, the infant was named Strachkvas, which means "a dreadful feast". There is also a tradition that Wenceslaus's loyal servant Podevin avenged his death by killing one of the chief conspirators, an act for which he was executed by Boleslav. The assassination of Wenceslaus has been characterized as an important turning point in early Bohemian history, as the rule of Boleslav I saw him renounce the Franks, centralize power in Bohemia and expand the territory of the polity. Veneration Wenceslaus was considered a martyr and saint immediately after his death, when a cult of Wenceslaus grew up in Bohemia and in England. Within a few decades, four biographies of him were in circulation. These hagiographies had