He became King of Italy when his Father's died in 810 and he reigned until 1818. His grandfather, Charlemagne let him inherit Italy.

Until 817, Charlemagne and Louis entrusted Bernard as their agent and he was well respected in Italy. Bernard was an intermediary in events in his sphere of influence.

Louis the Pious drew up an Ordinatio Imperii in 817. It outlined in detail the future of the Frankish Empire with the greatest portion of the territory going to Louis' eldest son, Lothair. Bernard did not receive anymore territory. Even tho he was confimed King of Italy, he would only be a vassal of Lothair.

Bernard was furious and began to plot with a group of magnates against Lothair. He was very upest about being a vassal of Lothair. However, his positon as King of Italy had actually not been changed. He could have continued to rule under the new system. But reports, although only partly true, was brought to Louis the Pious stating that his nephew Bernard was planning to set up and 'unlawful' and independent regime in Italy.

Therefore, Louis the Pious marched swiftly south to Chalon and Bernard and his group of magnates were taken by surprise. Bernard tried to negotiate terms but they were forced to surrender and Louis had them taken to Aix-la-Chapelle. They were all tried and dondemned to death. However, Louis was 'merciful' and comuted their sentences to blinding. So without killing Bernard it would tend to neutralise Bernard as a threat. However, the process of blinding was so traumatic for Bernard that died two days later.