The Death of Sigebert III and the…

656 CE

The Death of Sigebert III and the Usurpation of the Austrasian Throne by Grimoald (656 CE)

On February 1, 656 CE, King Sigebert III of Austrasia dies at age twenty-five, after a twenty-two-year reign. His six-year-old son, Dagobert II, is the rightful heir, but the powerful Mayor of the Palace, Grimoald the Elder, seizes the opportunity to remove the Merovingian line from power, installing his own son, Childebert the Adopted, as king.

1. The Coup: Grimoald’s Seizure of Power

With Sigebert III’s young son Dagobert II as heir, the Austrasian nobility expects a continued Merovingian rule.
Grimoald the Elder, already the most influential figure in the Austrasian court, orchestrates a political coupto install his own lineage on the throne.
Grimoald has Dagobert II kidnapped and exiled, ensuring he cannot reclaim power.

2. The Fate of Dagobert II: Exile to an Irish Monastery

Dagobert is initially placed under the care of Dido, Bishop of Poitiers, who arranges for him to be sent into exile.
He is taken to an Irish monastery, where he is raised in obscurity, far from the Frankish court.
This reflects a common Merovingian practice, where political rivals were often exiled to monasteries instead of being executed, reducing their threat.

3. Childebert the Adopted: A Non-Merovingian King in Austrasia

With Dagobert II removed, Grimoald declares his own son, Childebert the Adopted, as King of Austrasia.
This is unprecedented, as the Merovingians had ruled the Franks for over a century, and legitimacy was tied to dynastic heritage.
Grimoald’s move alienates both Austrasian and Neustrian factions, as it undermines the sacred lineage of the Merovingian kings.

4. The Aftermath: The Collapse of Grimoald’s Plan

While Grimoald briefly secures power, his usurpation is ultimately short-lived.
In 657 CE, Clovis II of Neustria has Grimoald captured and executed, restoring Merovingian rule over Austrasia.
Dagobert II remains in exile, and Austrasia eventually falls under the rule of Chlothar III, Clovis II’s successor.

Conclusion: A Failed Usurpation That Weakened the Merovingians

The death of Sigebert III in 656 CE and the subsequent coup by Grimoald mark a significant attempt to overthrow the Merovingian dynasty, demonstrating the growing power of the Mayors of the Palace. While Grimoald’s plan fails, it weakens Merovingian authority, foreshadowing the eventual rise of the Carolingians, who will succeed where Grimoald could not—replacing the Merovingians entirely.