[4][6] As a child, Dagobert lived under the care of the Carolingian dynasty forebears and Austrasian magnates, Arnulf of Metz and Pepin of Landen.

Dagobert made his courtier Gundoin—who incidentally established monasteries in Alsace and Burgundy[9]—the first duke of this new polity that was to last until the end of the Merovingian dynasty.

While Austrasian rulers such as Chlothar and Dagobert controlled these regions through part of the seventh-century, they eventually became autonomous kingdoms as powerful aristocratic families sought separate paths across their respective realms.

[12] Besides signing this treaty, Dagobert also took steps to secure trade across his empire by protecting important markets along the mouth of the Rhine at Duurstede and Utrecht, which in part explains his later determination to defend the Austrasian Franks from the Avar menace.

[13] Under the rule of Dagobert's father and like-minded Merovingians, Frankish society during the seventh-century experienced greater integration—the Catholic faith became predominant for instance—and a generally improved economic situation, but there was no initial impetus for the political unification of Gaul.

[16] When Charibert and his son Chilperic were assassinated in 632, Dagobert had Burgundy and Aquitaine firmly under his rule, becoming the most powerful Merovingian king in many years and the most respected ruler in the West.

[19] Taking advantage of the situation at the time, the Saxons offered to help Dagobert if he agreed to rescind the 500 cow yearly tribute to the Austrasians.

In 634, Dagobert appeased the rebellious nobles by putting his three-year-old son, Sigebert III, on the throne, thereby ceding royal power in the easternmost of his realms, just as his father had done for him eleven years earlier.

In historian Ian Wood's view, Dagobert's creation of a sub-kingdom for his son Sigibert had "important long-term implications for the general structure of Merovingian Francia.

[21] Dagobert was beloved in many ways according to Fredegar, who wrote that "He rendered justice to rich and poor alike," adding that, "he took little sleep or food, and cared only so to act that all men should leave his presence full of joy and admiration.

[24] Only thirty six when he died, Dagobert is considered the last of the great Merovingian kings by most historians, but this does not mean there was a major waning in Frankish power, especially in light of the writings of Paul the Deacon and John of Toledo.

"[24] Despite having more or less united the Frankish realms, he likely was not expecting unitary rule to continue given the diverging interests of the Austrasian and Neustrian Franks, atop those of the Aquitanians and Burgundians.

The Merovingian boy-kings remained ineffective rulers who inherited the throne as young children and lived only long enough to produce a male heir or two, while real power lay in the hands of the noble families who exercised feudal control over most of the land.

[citation needed] Shortly after his marriage to Nanthild, a woman called Ragnetrude bore Dagobert I a son, Sigebert III (b.