 In 1769, Prince Charles of Hesse was appointed royal Governor of the twin duchies of Schleswig and Holstein (initially only the royal share, so-called Holstein-Glückstadt before in 1773 the king also acquired the ducal share in Holstein) on behalf of the government of his brother-in-law, King Christian VII of Denmark and Norway.Charles took up residence at Gottorp Castle in Schleswig with his family.They would have their third child Frederick there in 1771.