Count of Toulouse (814-835) and ducem (duke) and marquis of Septimania (832-835). Was councelor of Pipin of Aquitaine from 816. In November 831, Pipin of Aquitania was revolted against his father. Berenguer advises to him be not revolted but Bernat of Septimania instigates to him to the revolt. In the beginning of 832 Louis the Pious begins the campaign against his rebellious son. Berenguer, loyal to the Emperor penetrated in the dominances of Bernat being empowered of some of they, with safety of Roussillon (with Vallespir), probably also of Rasez and Conflent. February 2, 832 Berenguer already was in Elna . Finally in autumn of the same year, successive victories of the imperial forces, compel to Pipin and Bernat to appear before the Emperor (October). Pipin was dispossessed of his kingdom and sent prisoner to Trier, being conceded his territories to Charles (the Bald). Bernat was accused of infidelity and dismissed of all his possessions in Septimania and Gothia that they were delivered to Berenguer of Toulouse. Probably Gaucelm was also dispossessed of his counties, but by a time preserved the county of Empúries no respecting his dismissal. Finally in the year 833, by the mediation of the abbot Angenís of Fontanelle, resigned and departed toward properties of the family in Burgundy, togheter his staunch liutenant Sanila. Gaucelm and Sanila were executed by have defended Chalon-sur-Saône against the assault of Lothar in 834 (even it was murdered a nun, sister of Gaucelm and of Bernat of Septimania, called Gerberga).

In 833 Aznar I Galíndez, count of Urgell and Cerdagne, usurped the counties of Pallars and Ribagorza, under Berenguer rule, as part of the civil war in the Empire.

In the war of 834, where Lothar was defeated, Bernat and Gaucelm fought to the side of Pipin of Aquitania, one of those which finally left victorious. Bernat of Septimania, alleging the high price of blood paid in the struggle, claimed the return of his old dominances. Berenguer was possesing them legally and his party also left winning of the struggle, though weakened. Aznar I Galíndez was deposed as count of Pallars and Ribagorza (reunited nominally to Tolosa), and as count of Urgell and Cerdagne that were granted to Sunifred of Carcasonne , son of Bello of Carcasonne and brother of the ruler Oliba of Carcasonne . Sunifred took Cerdagne easely but Aznar I resisted in Urgell (until 838), Pallars (until c. 843) and Ribagorza (until c. 844). The counties of Empúries and Roussillon were granted to the brothers Sunyer and Alaric , of unknow orign, but perhaps also from the dinasty of Carcasonne.

The Emperor was doubting as to act. In June 835 summoned to Bernat and Berenguer to an Assembly in Cremieux , near Lyon, where would be taken a decision, but in the trip Berenguer died in unexpected form. Already without obstacle, the Emperor attributed the counties of the regións of Septimania and Gothia and Toulouse to Bernat.