in fall 1550, isabella's troops defended alba iulia, but had to agree to a truce. she gained support from nobility in the diet of aiud, but her forces were defeated near cenad and she was besieged in buda. in july 1551, facing superior forces, isabella surrendered and signed the treaty of weissenburg. she agreed to give up transylvania in exchange for opole, racibórz, and other territories so that her annual income would be 25,000 florins. for her domains in hungary, which were valued at 140,000 florins, isabella was to receive ziębice, ząbkowice śląskie, and 100,000 florins in cash. john sigismund was to marry one of ferdinand's daughters. in august, isabella gave up the holy crown of hungary. according to marcin bielski, the cross atop of the crown was broken off and kept by john sigismund who hoped one day to reunite the pieces. at the same time, john sigismund was betrothed to 4-year-old joanna of austria.