メルセン条約
Added to his possible paid military service to Lothair II, his close relations with the Frankish kings suggests he may have had a fiefdom in Frisia, perhaps having succeeded his father there in the 840s. If so, then Charles became his overlord by the Treaty of Meerssen in 870. His major Viking activities took place, according to the annals, in West Francia and "across the water", presumably referring to the British Isles. According to the "Annales Bertiniani", in the autumn of 873 Charles the Bald warned his leading vassals in the north of his kingdom to beware of Rodulf possible treachery. Janet Nelson, commenting on the "Annales", speculated that Rodulf was conspiring with Charles rebellious younger son Carloman.