On 1 June 1697, Elector Frederick Augustus I, "the Strong" (1694–1733) converted to Catholicism and was subsequently elected King of Poland and Grand duke of Lithuania. This marked a personal union between Saxony and the Commonwealth of Two Nations that lasted almost 70 years with interruptions. The conversion of the Elector raised fears among many Lutherans that Catholicism would now be re-established in Saxony. In response, the Elector transferred his authority over Lutheran institutions to a government board, the Privy Council. The Privy Council was composed exclusively of Protestants. Even after his conversion, the Elector remained the head of the Protestant body in the Reichstag, despite an unsuccessful attempt by Brandenburg-Prussia and Hanover to take over the position in 1717–1720.