Richelieu is also known by the sobriquet l' Ã minence rouge ( `` the Red Eminence '' ) , from the red shade of a cardinal 's vestments and the style `` eminence '' as a cardinal . Richelieu is also known by the sobriquet l' Ã minence rouge ( `` the Red Eminence '' ) , from the red shade of a cardinal 's clerical dress and the style `` eminence '' as a cardinal .