The title Duke [and Prince] of the Franks (dux [et princeps] Francorum) has been used for three different offices, always with "duke" implying military command and "prince", on those occasions when it was used either with or in preference to "duke", implying something approaching sovereign or regalian rights. The term "Franks" may refer to an ethnic group or the inhabitants of a territory called "Francia", named after the original Franks. The first office was that of the mayors of the palace of the Merovingian kings of the Franks, whose powers increased as those of the kings declined. The second was that of the second-in-command to the early kings of France, the last incumbent of which succeeded to the throne in 987. This title was sometimes rendered Duke of France (dux Franciae). The third instance was that of the rulers of the Frankish-inhabited lands of Germany, the so-called "tribal" duchy of Franconia.