Isabella and Martinuzzi left Buda on 5 September 1541, taking John Sigismund and the Holy Crown with them. She and her son settled in Lippa, which was the center of an old domain of the Zápolya family. The delegates of the counties of John Sigismund's realm met in Debrecen on 18October. They swore fealty to him and acknowledged the sultan's suzerainty. Martinuzzi signed a treaty with FerdinandI's representative, Caspar Serédy, in Gyalu (now Gilău in Romania) on 29December. According to the Treaty of Gyalu, Hungary was to be reunited under the rule of Ferdinand, but John Sigismund's right to the Zápolyas' domains in Upper Hungary was confirmed.