Liber Historiae Francorum
He was a son of Childebert III. He succeeded his father as the head of the three Frankish kingdoms—Neustria and Austrasia, unified since Pippin's victory at Tertry in 687, and the Kingdom of Burgundy—in 711. Real power, however, still remained with the Mayor of the Palace, Pippin of Herstal, who died in 714. Pippin's death occasioned open conflict between his heirs and the Neustrian nobles who elected the mayors of the palace. As for Dagobert himself, the Liber Historiae Francorum reports he died of illness, but otherwise says nothing about his character or actions.