 However, it lost forever the possibility of extending its territory along the lower course of the Elbe into the lands of the Archbishopric of Magdeburg, even though they were under the administration of the Wettin Duke, Augustus of Saxe-Weissenfels.Upon his death in 1680, the secularised Duchy of Magdeburg fell to the "Great Elector" Frederick William of Brandenburg, which confirmed the primacy of Brandenburg-Prussia under the Protestant Hohenzollern dynasty.In 1653, the Saxon elector became the head of the "Corpus Evangelicorum", the union of the Protestant Imperial Estates.