Son of Sigebert and Brunehaut, Childebert inherited Austrasia upon the assassination of his father. He is then adopted by his uncle Gontran, but later passes under the tutelage of Chilpéric (who murdered his father). But under the influence of his mother Brunehaut, Childebert returned to Gontran with whom he signed an alliance linking Burgundy to Austrasia. On the death of Gontran, Childebert therefore reigns over Austrasia and Burgundy. These two kingdoms are shared at his death between his two sons:Théodebert II and Thierry II.
Lawyer in 1781 then judge in 1782 in Arras, he participated in the drafting of the notebooks of grievances and was elected deputy of the third estate in 1789. He thus participated in the states general the same year. He became the principal leader of the Jacobin Club in 1791, defending the freedom o