The first care of the new elector was to come to terms with John Frederick, and to strengthen his own hold upon the electoral position. This object was secured by a treaty made at Naumburg in February 1554, when, in return for the grant of Altenburg and other lands, John Frederick recognized Augustus as elector of Saxony.
Her parents were Joachim Frederick, Margrave of Brandenburg and his first wife Catherine of Brandenburg-Küstrin. Christian met her on his journey in Germany in 1595 and decided to marry her. In 1596, Anne Catherine and her parents were present at his coronation, and the next year, the marriage was arranged.