b. Nov. 1206, d. near Buda (Budapest, Hungary), May 3, 1270, 1235-1270 King of Hungary. When Hungary was conquered by the Mongols led by Batu Khan in 1241, Bela IV fled to Austria and ceded three western border counties (Moson, Sopron and Vas) to Duke Friedrich II for help against the Mongols. After the Mongols´ retreat he reclaimed the three counties and war broke out, in which Duke Friedrich II died on June 15, 1246. Bela IV then claimed Austria and Styria and 1253 launched an attack on Austria and Moravia. In the Treaty of Buda (April 3, 1254) he acquired Styria up to the present northern border of the province but without the area around Wiener Neustadt and the Traungau region. However, after his defeat at Groissenbrunn, Styria was assigned to Otakar II of Bohemia in the Treaty of Vienna (March 31, 1261).
Literature#K. Lechner, Die Babenberger, 41992.