Robert was killed fighting the Vikings in 866, revealing how the boundaries of the marches did not affect the raiders with which the marcher margraves had to deal nor prevent the two margraves from cooperating in each other's territories against the common enemies of the Franks. Hugh the Abbot succeeded to Robert's office and title. In 885, Charles the Fat succeeded to power in West Francia and after Hugh's death in 886, Charles gave the title to Robert the Strong's son, Odo. After Charles' death in 888, Odo became king of the Franks and appointed Robert I margrave of the Breton March. Odo died in 898 and was succeeded as king by Charles the Simple who confirmed Robert's titles and possessions.