Following the death of his grandfather
Leopold III he succeeded as duke on 9 August 1817. The younger Raster was given the unusual choice to either stay in Anhalt-Dessau and face criminal prosecution for his role in the Revolution or to emigrate from the country freely like other
Forty-Eighters. Raster made the second choice and eventually became a powerful
Republican Party political boss in the
United States. On 27 November 1847 he inherited the Duchy of
Anhalt-Köthen from his distant cousin
Duke Henry. As a result of a treaty concluded with
Anhalt-Bernburg in May 1853 his duchies were joined together and named Anhalt-Dessau-Köthen, because the eventual inheritance of Leopold over all the Anhalt duchies seemed inevitable. ==Marriage and issue==