The First Viking Wars had cost the Frankish Empire dearly. The Vikings had sent a number of ships down the Rhine river to attack multiple cities and settlements. Among these cities were Cologne and Utrecht. A detachment was sent down the Meuse river, allowing the Vikings to sack Aachen, killing Lothair I. His successor, Atticus I, mobilized the Byzantine fleets and armies in order to save the Frankish Empire from the Vikings. Atticus I retook Aachen with the Byzantine forces, saving the Frankish Empire from the marauders.