Jews in 1244. However Frederick was killed in the Battle of the Leitha River against the Hungarians, and had no surviving children. Thus the Babenburg dynasty became extinct in 1246. Interregnum (1246–1278) What followed was an interregnum, a period of several decades during which the status of the country was disputed, and during which Frederick II's duchy fell victim to a prolonged power play between rival forces. During this time there were multiple claimants to the title, including Vladislaus, Margrave of Moravia son of King Wenceslaus I of Bohemia. King Wenceslaus aimed at acquiring the Duchy of Austria by arranging the marriage of Vladislaus to the last Duke's niece Gertrud, herself a potential heir and claimant. According to the Privilegium Minus issued by Emperor Frederick Barbarossa in 1156, the Austrian lands could be bequeathed through the female line. Vladislaus received the homage of the Austrian nobility, but died shortly afterwards, on 3 January 1247, before he could take possession of the duchy. Next came Herman of Baden in 1248. He also made claim by seeking Gertrud's hand but did not have the support of the nobility. Herman died in 1250, and his claim was taken up by his son Frederick, but his claim was thwarted by the Bohemian invasion of Austria. In an attempt to end the turmoil a group of Austrian nobles invited the king of Bohemia, Ottokar II Přemysl, Vladislaus' brother, to become Austria's ruler in 1251. His father had attempted to invade Austria in 1250. Ottokar then proceeded to ally himself to the Babenbergs by marrying Margaret, Duke Frederick II's sister and daughter to Leopold VI, therefore making him a potential claimant to the throne, in 1252. He subdued the quarrelsome nobles and made himself ruler of most of the area, including Austria, Styria (which was previously under the rule of Hungary) as well as Carniola and Carinthia, both of which he had claimed by a dubious right of inheritance. Ottokar was a lawmaker and builder. Among his achievements was the founding of the Hofburg Palace in Vienna. Ottokar was in a position to establish a new empire, given the weakness of the Holy Roman Empire on the death of Frederick II (1220–1250) particularly after the Hohenstauffen dynasty was ended in 1254 with the death of Conrad IV and the ensuing Imperial interregnum (1254–1273). Thus Ottokar put himself forward as a candidate for the imperial throne, but