While initially the Carantanian rulers joined the tribal union of Samo's Empire, Prince Boruth around 743 turned to Duke Odilo of Bavaria to ask for support against the Avar invaders. Aid was granted, however at the price of Bavarian overlordship. The Carantanian principality became part of the Bavarian stem duchy, while the area was Christianised for the second time by missionaries from the Salzburg diocese. Bishop Vergilius had Prince Boruth's son Cacatius and his nephew Cheitmar brought up in Christian faith. In 767, at their request, the bishop sent Modestus to Carantania as a vicar and had churches built at Teurnia and Maria Saal. Upon a pagan uprising in 772, the forces of Odilo's son Duke Tassilo III of Bavaria again subdued the Carantanian lands.