Treaty of Weissenburg

The Treaty of Weissenburg (Vertrag von Weißenburg or Weißenburger Vertrag) declared Archduke Ferdinand of Austria the ruler of Royal Hungary and Transylvania. It was signed in Weissenburg (Gyulafehérvár) on July 19, 1551. The territory had previously been ruled by John Zápolya's widow, Isabella Jagiełło.