Rudolf I or Rudolf of Hapsburg (rōˈdŏlf) [key], 1218–91, German king (1273–91), first king of the Hapsburg dynasty. Rudolf's election as king ended the interregnum (1250–73), during which time there was no accepted German king or Holy Roman emperor. The election was prompted by Pope Gregory X, who needed the support of a strong German ruler to counter the power of Charles I of Anjou in Italy. Rudolf's election was contested by the powerful King Ottocar II of Bohemia. Rudolf finally defeated Ottocar at Marchfeld (1278) and invested (1282) his own sons Albert (later King Albert I) and Rudolf with Austria, Styria, and Carniola, which he had won from Ottocar; these lands became the core of the Hapsburg possessions. Rudolf thus laid the foundations for a strong kingship based on large dynastic holdings. In Germany, Rudolf attempted to recover the rights lost to the crown during the interregnum. He issued local land peaces to overcome internal anarchy and imposed taxes on the imperial towns in order to strengthen the central government, but these measures had little success. In his Italian policy Rudolf attempted to conciliate the new pope, Nicholas III (reigned 1277–80), in the hope of securing the pope's approval for his coronation as Holy Roman emperor; Rudolf renounced his sovereignty over the Papal States and sought to bring about the withdrawal of the house of Anjou from central Italy. With Nicholas's death, however, and the election of an anti-German pope, Rudolf's plans for imperial coronation fell through. He also failed to have his son Albert elected king, which would have insured Albert's succession as emperor. Instead, Adolf of Nassau succeeded Rudolf.