in the lands to the east of the Tisza. However, the dowager queen died at the age of 40 on 18September 1559. King-elect Start of personal rule John Sigismund's rule began with his mother's death. Rather than adopting a new title, he continued to style himself rex electus (king-elect). Mihály Csáky, Christopher and Stephen Báthory, and his mother's other advisors continued to participate in state administration. John Sigismund sent envoys to Ferdinand to propose marriage with one of Ferdinand's daughters, but also to announce his claim to the parts of Hungary under Ferdinand's rule. His demands were rejected, but peace was preserved. John Sigismund showed a particular interest in religious matters and initiated several debates among the representatives of diverse theological schools. The first debate was held between Lutheran and Calvinist priests in Medgyes (now Mediaș in Romania) in January 1560. A year and a half later, John Sigismund sent letters to the University of Wittenberg and other theological centers in Germany to seek advice on the main points of the two Protestant schools of thought. Melchior Balassa, one of the wealthiest lords in John Sigismund's realm, deserted to Ferdinand in December 1561. John Sigismund moved to seize Balassa's domains, but his army was routed at Hadad (now Hodod in Romania) on 4 March 1562. Stirred up by Balassa, the Székely commoners rose to restore their ancient liberties (including exemption from taxes), which had been restricted in the 1550s. John Sigismund's army routed them in May, and their leaders were impaled or mutilated. The Diet adopted new laws to restrict the privileges of the Székelys, including a ban on the employment of commoners as jurors. Two new royal castles named Székelytámad ("Székely-assault") and Székelybánja ("Székely-regret") were erected in the Székely Land. After Balassa's revolt, most counties outside Transylvania changed allegiance from John Sigismund to Ferdinand. To persuade Ferdinand to renounce the counties, John Sigismund even offered not to style himself king, but this was rejected in July 1562. John Sigismund, originally Roman Catholic, converted to Lutheranism before the end of 1562. However, debates between Lutheran and Calvinist theologians continued. John Sigismund appointed his court physician, Giorgio Biandrata (who as an Anti-Trinitarian did not share either the Lutheran or the Calvinist view) to head a synod to reconcile the Lutheran and the Calvinist clergymen, but their differences proved insuperable in April 1564. The Diet acknowledged the existence of a separate Calvinist