After Matthias I's death, the assembly of the Estates, called Diet, began to function as a regular organ of power. The peasantry suffered most from the rule of the Estates, for instance, by the limitation of their right to free movement. In 1514 thousands of peasants who had been summoned to Buda (now Budapest, in modern Hungary) to join the crusade proclaimed by Pope Leo X against the Ottomans turned the weapons against their masters. The rebels, led by the Székely George Dózsa, occupied several towns, such as Oradea and Şoimoş, but on July 15 John Szapolyai, the "voivode" defeated them at Timișoara. As a retaliation, the Diet decreed that peasants were to be tied to the land "perpetually".