Suleiman sent messages to the Transylvanian lords in 1555, demanding they obey John Sigismund without resistance. Before the end of the year, the representatives of the Three Nations petitioned Ferdinand either to send reinforcements or to absolve them from their oath of fealty. Petrovics stormed into Transylvania in early 1556. The Diet swore an oath of fealty to John Sigismund on 12March 1556, referring to him as "the son of King John". The envoys of the Diet departed for Poland on 1June to persuade Isabella and her son to return. Two weeks later, Ferdinand informed Suleiman that he was ready to withdraw his troops from John Sigismund's former realm.