 Complete the following phrase:  In 1538, in the Treaty of Nagyvárad, Ferdid induced the childless Zápolya to name him as his successor. But in 1540, just before his death, Zápolya had a son, John II Sigismund, who was promptly elected King by the Diet. Ferdid invaded Hungary, but the regent, Frater George Martinuzzi, Bishop of Várad, called on the Ottomans for protection. Suleiman marched into Hungary see 