The siege was part of a struggle between the Habsburgs and the Ottomans following the death of the ruler of Hungary, John Zápolya, on 20 July 1540. This is part of the "Age of castle wars" in Hungarian history. Suleiman had captured the cities of Buda and Pest in 1541, giving him a powerful control over central Hungary. The Province (Beylerbeylik) of Buda was created in this occasion.