In 1528 John fled Hungary for Poland, where he stayed with Prince Jan Amor Tarnowski. In 1529 John approached the Ottomans, and agreed to make Hungary a vassal state in return for recognition and support. Sultan Suleiman the Magnificent accepted, and sent Ottoman armies to invade Austria (which included the Siege of Vienna), a war which lasted till 1533. This allowed John to regain his position in Hungary in 1529, by the efforts of Frater George Martinuzzi, despite the association with the Ottomans which tainted him at the time. Martinuzzi became royal treasurer and John's most trusted minister.