the Mongols now set their sights on Vienna. A minor raiding squadron started pillaging Wiener Neustadt in Southern Vienna, but Duke Frederick together with his knights and foreign allies, defeated them and drove them out. The Austrians would again defeat the Mongols in the River March in Theben. Afterwards, the Mongols never again tried to invade Austria. The conflict with Bohemia was settled by the engagement of his niece Gertrude of Babenberg with King Wenceslaus' eldest son Margrave Vladislaus of Moravia. Negotiations with the emperor about the elevation of Vienna to a bishopric and of Austria (including Styria) to a kingdom were initiated, however, on condition that the duke's niece Gertrude now would have to marry the fifty-year-old emperor, who moreover had recently been banned by Pope Gregory IX and needed allies. In 1245 the terms were arranged, but the willful young girl, then in her late teens, refused to appear in the consummation ceremony at the diet of Verona. In the year before his death, Duke Frederick finally succeeded in gaining the rule over the March of Carniola from the Patriarchate of Aquileia, but upon his death it fell to the Carinthian duke Bernhard von Spanheim. Duke Frederick's ambitious plans were dashed when he died at the Battle of the Leitha River, in another border conflict he had picked with the Hungarian king Béla IV. He is buried at Heiligenkreuz Abbey. Legacy As the Austrian Privilegium Minus of 1156 also allowed women to inherit, Frederick's sister Margaret and his niece Gertrude would have been entitled to the throne. Shortly after the death of her uncle, Gertrude first married her fiancé Vladislaus of Moravia, who nevertheless died in the next year, then Margrave Herman VI of Baden, who did not manage to maintain his position in Austria, and finally in 1252 Prince Roman Danylovich, a younger brother of Knyaz Lev I Rurik, son-in-law of the Hungarian king, who also ended in divorce in 1253. In the same year the Bohemian Přemyslids made a second attempt to confirm their claims to the Austrian and Styrian duchies by arranging the marriage between Gertrude's aunt Margaret of Babenberg and King Wenceslaus' son Ottokar II, more than twenty years her junior. Subsequently, Austria became a field of conflict between the Přemyslids and the Hungarian Árpád dynasty, in which Ottokar at first would prevail defeating King Béla at the 1260 Battle of Kressenbrunn, until finally