Meanwhile , Frederick I 's son Henry VI , holding the imperial stake .
His troops seized most of Henry the Lion 's allodially owned Guelphic possessions around the city of Brunswick , but not the city itself .
Meanwhile , Frederick I 's son Henry VI , holding the imperial stake , and his troops seized most of Henry the Lion 's allodially owned Guelphic possessions around the city of Brunswick , but not the city itself .