 John Sigismund and Hasan Pasha stormed into Upper Hungary in March 1567. However, John Sigismund was taken seriously ill in summer. The Transylvanian lords pledged to respect his last will when electing his successor. The Ottoman Sultan Selim II granted the Transylvanian lords the right to freely elect their monarch, only preserving the right to approve their decision. Before long, John Sigismund recovered.
