He plotted against his uncle, Emperor Louis the Pious, when the latter's Ordinatio Imperii made Bernard a vassal of his cousin Lothair.

[2] Certain of his counselors, including Count Eggideo, and his chamberlain Reginhard, persuaded Bernard that this arrangement threatened his position.

Louis 'mercifully' commuted their sentences to blinding, which would neutralize Bernard as a threat without actually killing him; however, the process of blinding (carried out by means of pressing a red-hot stiletto to the eyeballs) proved so traumatic that Bernard died in agony two days after the procedure was carried out.

At the same time, Louis also had his half-brothers Drogo, Hugh and Theoderic tonsured and confined to monasteries, to prevent other Carolingian offshoots challenging the main line.

In 822, Louis made a display of public penance at Attigny, where he confessed before all the court to having sinfully slain his nephew; he also welcomed his half-brothers back into his favour.

It has been argued by some historians that his behaviour left him open to clerical domination, and reduced his prestige and respect amongst the Frankish nobility.