In 1260, Ottokar defeated Béla IV, king of Hungary in the Battle of Kressenbrunn near the Morava river, where more than 200,000 men clashed. He ruled an area from Austria to the Adriatic Sea. From 1273, however, Habsburg king Rudolf began to reassert imperial authority, checking Ottokar's power. He also had problems with rebellious nobility in Bohemia. All of Ottokar's German possessions were lost in 1276, and in 1278 he was abandoned by part of the Czech nobility and died in the Battle on the Marchfeld against Rudolf.