Bernard, a grandson of Charlemagne through Pepin of Italy, saw this as a potential threat to ultimately take over Italy. Some of his counselors advised him to act, even though he had always had a decent relationship with his uncle Louis. Louis started hearing rumors that Bernard was planning to make Italy independent, so he marched an army south.
Bernard met him at Chalon to talk, but was captured and taken to the palace at Aachen where he and others were tried for conspiracy and treason. Although an appropriate sentence was execution, Louis decided to simply remove Bernard's ability to rule by blinding him and his co-conspirators. This was done by pushing a red-hit stiletto to the eyeballs. Unfortunately, the procedure went too far, and Bernard died in agony within two days. Above you see his tomb, along with his consort, Cunigunda of Laon. As mentioned here, Louis also forced other relatives who might have become the focus of rebellion into monasteries.
One of the supposed co-conspirators was Theodulf of Orléans, but proof was lacking. Still, Theodulf was removed from his bishopric and imprisoned in a monastery in Angers in 818. Released in 820, he tried to go to Orléans, but died along the way, on 18 January 821. His body was taken back to Angers for burial.
The Kingdom of Italy was given to Lothair. Italy's feared fate had become fact, perhaps because Bernard tried to prevent it.
Not long after, in 822, the affair of the blinding had an epilogue, which would require a trip to Attigny in northeast France. I will take you there tomorrow and explain.