The nation which stood in such great need of peace, was unfortunately doomed never to enjoy its blessings. Béla himself, as soon as he had gained sufficient strength, deemed it his first duty to punish Frederic, the faithless Austrian duke, and to recover the treasures retained by the latter’s treachery. The war between the two neighbors began in 1246. The contest in itself was of no great significance but its consequences were highly important. Béla achieved, with the help of his Kun warriors, a complete triumph over Frederic, who lost his life on the battle-field. Frederic was the last of the Babenberg line, and the inheritance of the Babenbergs, the Austrian principalities, were, through his death, left without a master. Béla coveted for himself the masterless countries, but was opposed in his schemes in that direction by Ottokar, the powerful king of Bohemia, who then already labored for the realization of his ambitious dream, the founding of a great Slavic empire. The Hungarian king could not expose his country to the dangers involved in the erection of such a Slavic empire along the western borders, and was therefore opposed, from the beginning, to Ottokar’s aspirations. The contest between Hungary and Bohemia was at first waged for the Babenberg possessions, but its original cause was lost sight of, and the war continued for many years, to terminate only with the overthrow of Ottokar and the ruin of his empire. Béla was engaged in these wars during the last years of his reign, and they were continued by his son Stephen V., and his grandson Ladislaus IV.