http://en.wikipedia.org/wiki/Catherine_of_Brandenburg

Catherine of Brandenburg (Königsberg, May 28, 1604 – August 27, 1649, Schöningen) was ruler of Transylvania between 1629 and 1630.

She was the daughter of John Sigismund, Elector of Brandenburg and Anne of Prussia.

On March 2, 1626 she married Gabriel Bethlen, prince of Transylvania, who made her his successor in June 1626.

When the prince died on November 25, 1629, she tried in vain for a year to hold on to the throne, supporting herself on her favorite Istvan Csaky. Her policy was to bring Transylvania back under the influence of Holy Roman Emperor Ferdinand II, but she was forced to abandon power on September 21, 1630.

The Sublime Porte, first chose her brother-in-law István Bethlen as successor, but finally she was succeeded by George I Rákóczi. The new prince George I Rákóczi was elected on December 1, 1630.

Catherine of Hohenzollern moved back to Germany where she converted to Catholicism in 1633 and married in 1638 Francis Charles of Saxe-Lauenburg. She died on August 27, 1649.

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http://hu.wikipedia.org/wiki/Brandenburgi_Katalin