sed to appear before the
princes, Frederick placed him under the ban, declared the duchies of
Austria and Styria to be vacant, and, aided by the king of Bohemia, the
duke of Bavaria and other princes, invaded the country in 1236. [Sidenote:
End of the House of Babenberg.] He met with very slight opposition,
declared the duchies to be immediately dependent upon the Empire, made
Vienna an imperial city, and imposed other changes upon the constitution of
Austria. After his departure, however, the duke returned, and in 1239 was
in possession of his former power, while the changes made by the emperor
were ignored. Continuing his career of violence and oppression, Duke
Frederick was killed in battle by the Hungarians in June 1246, when the
family of Babenberg became extinct.

[Sidenote: Dispute as to the Austrian succession.]

The duchies of Austria and Styria were now claimed by the emperor Frederick
II. as vacant fiefs of the Empire, and their government was entrusted to
Otto II., duke of Bavaria. Frederick, however, who was in Italy, harassed
and afflicted, could do little to assert the imperial authority, and his
enemy, Pope Innocent IV., bestowed the two duchies upon Hermann VI.,
margrave of Baden, whose wife, Gertrude, was a niece of the last of the
Babenbergs. Hermann was invested by the German king, William, count of
Holland, but he was unable to establish his position, and law and order
were quickly disappearing from the duchies. The deaths of Hermann and of
the emperor in 1250, however, paved the way for a settlement. Weary of
struggle and disorder, and despairing of any help from the central
authority, the estates of Austria met at Truebensee in 1251, and chose
Ottakar, son of Wenceslaus I., king of Bohemia, as their duke. [Sidenote:
Ottakar of Bohemia, duke.] This step was favoured by the pope, and Ottakar,
eagerly accepting the offer, strengthened his position by marrying
Margaret, a sister of Duke Frederick II., and in return for his investiture
promised his assistance to William of Holland. Styria appears at this time
to have shared the fortunes of Austria, but it was claimed by Bela IV.,
king of Hungary, who conquered the land, and made a treaty with Ottakar in
1254 which confirmed him in its possession. The Hungarian rule was soon
resented by the Styrians, and Ottakar, who had become king of Bohemia in
1253, took advantage of this resentment, and interfered in the affairs of
the duchy. A war with Hungary was