 Svatopluk I of Great Moravia intervened as an ally of Aribo because he had been at war with William and Engelschalk when the two died in 871.The "Wilhelminers" were the descendants of William I, father of the two late margraves.At first, the rebels were successful, but Aribo appealed to not only Moravia, but also the Emperor Charles the Fat, who confirmed Aribo in his post, to which he had been appointed by Charles' father, Louis the German, back in 871.