During his career, Bernard was one of the closest counsellors of the Emperor Louis the Pious, a leading proponent of the war against the Moors, and was an opponent of the interests of the local Visigothic nobility in Iberia.
His name and title as they appear in several primary sources were: Bernard is first attested in historical records as one of four sons in a document of his father's dating to 14 December 804 concerning the foundation of the monastery of Gellone.
He first attracted the attention of higher nobility by quelling the local revolt of a nobleman named Aisso, who was perhaps a Visigothic lieutenant of the deposed Bera, Count of Barcelona.
To counter these reinforcements, Aisso sent his brother to request help from Abd ar-Rahman II, Emir of Córdoba, the only potential ally powerful enough to threaten the Franks.
Abd ar-Rahman sent the general Ubayd Allah Abu Marwan to Zaragoza in May 827, from whence he invaded the territory of Barcelona, reaching the city itself in the summer.
Though the ravaged county of Ausona, a dependency of Barcelona, remained depopulated into the mid-ninth century, its ruin was attributed to the late arrival of Hugh and Matfrid.
Louis summoned Bernard to replace his son at court, granting him the title of camerarius or Chamberlain and the custody of the young Charles, then just Duke of Alsace, Alemannia, and Rhaetia, but later destined to be king of West Francia.
[8] Thegan of Trier, in his Gesta Hludowici, recorded that Bernard was accused of having an illicit relationship with Empress Judith of Bavaria, but considered these rumours to be lies.
His life under threat, as the three elder children of Louis supported the opposition against him, Bernard abandoned the court and, according to the Annales Bertiniani, returned to Barcelona.
Subsequently, in another assembly at Aachen in February 831, he proceeded to divide the Empire, giving Gothia to Charles, although the division would not be effective until his death.
The only territories not returned were Empúries and Roussillon, which had already been granted to Sunyer I and Alaric, respectively, and Urgell and Cerdanya, which had been detached from Toulouse by the usurper Aznar I Galíndez.
Bernard avoided participating in the Battle of Fontenay-en-Puisaye (25 June 841), where Charles the Bald and Louis the German defeated their brother Lothair, who retreated to the south with his army.
During Charles the Bald's campaign in Aquitaine (842), he decided to punish Bernard, dispossessing him of the county of Toulouse in favor of Acfred (July).
Various other events—renewed Viking invasions and Breton raids—compelled an end to the internal civil struggles afflicting the Empire and, in August 843, the Treaty of Verdun was signed between the three brothers: Charles, Louis, and Lothair.
The following month, Pepin II and Bernard's son William dealt a severe blow to Charles in the Angoumois on 14 June.