Excerpts from Books and Wikipedia
"Dagobert I was the last of the Merovingian kings to rule over a united Frankish kingdom and his death, on January 19, 639, was followed by the slow decline of a dynasty that had ruled since Clovis I, more than one hundred years earlier. . . . He patronized the arts, revised Frankish law, encouraged learning, and founded the first abbey of Saint Denis. Dagobert was succeeded by his sons, Sigebert III and Clovis II, who came to be known as the roi faieant ('do nothing') kings because they did little else but father heirs. Real power lay with the nobility, a situation that lasted until 751 when Peppin the Short deposed the last Merovingian king, Chideric III. Peppin the Short was the first Carolingian king and the father of Charlemagne the Great." [1001 Days]