Sigebert III

Sigebert III (c. 630–656/660) was the king of Austrasia from 634 to his death probably on 1 February 656, or maybe as late as 660. He was the eldest son of Dagobert I.

To satisfy the Austrasian aristocracy, who exercised a certain autonomy, Sigebert's father gave him the kingdom of Austrasia although it remained part of the larger Frankish realm. On the death of Dagobert, Sigebert ruled Austrasia independently, and free from any subjection to Neustria. Under the tutelage of Blessed Pepin of Landen and other saints of the time, the young king grew into pious adulthood.

He tried in vain to add Thuringia to his kingdom, but was defeated by Duke Radulph in 640. Though only ten years of age, he was the leader of his army. The "Chronicle of Fredegar" records that the rout left him weeping in his saddle. From this, we can surmise that, at least in part, the downfall of the Merovingian dynasty was a result of child rule, for both Sigebert and his younger brother Clovis II, who ruled in Neustria, were prepubescent children who could not fight on the field and whose regents had their own interests at heart.

It was under his reign that the mayor of the palace began to play the most important role in the political life of Austrasia. That mayor, Grimoald, the son of Pepin I, managed to convince the king to adopt his son Childebert. When Sigebert finally had a son of his own, the future Dagobert II, the mayor of the palace felt threatened, and on the death of Sigebert (at the age of 25) he exiled the young Dagobert to Ireland. Sigebert's remains, defiled during the French Revolution, are preserved in the cathedral at Nancy.

Though not a success as a king, he was revered as the founder of numerous monasteries, hospitals, and churches. He is regarded as a saint by the Roman Catholic Church and is the patron saint of Nancy.

He has been described as the first "roi fainéant"—do-nothing king—of the Merovingian dynasty.