Treaty of Nagyvárad
The Treaty of Grosswardein or Treaty of Nagyvárad was a secret peace agreement between Ferdinand I of the Holy Roman Empire and the John Zápolya signed in Grosswardein / Várad (modern-day Oradea, Romania) on February 24, 1538. In the treaty the medieval Kingdom of Hungary was divided by them.
Zápolya was recognized as King of Hungary, while Ferdinand retained the western parts of the Hungarian Kingdom, and was recognized as heir to the Hungarian throne. John Zápolya was left with the remaining two-thirds of the Kingdom. A short while before Zápolya's death, his wife bore him a son, John II Sigismund Zápolya. Zápolya died in 1540, and John Sigismund was recognized as King of Hungary by the Hungarian nobility. The Ottoman Sultan Suleyman the Magnificent also recognized John Sigismund as King and as his vassal.