In 673, Chlothar III died and some Neustrian and Burgundian magnates invited Childeric to become king of the whole realm, but he soon upset some Neustrian magnates and he was assassinated (675).

The reign of Theuderic III was to prove the end of the Merovingian dynasty's power. Theuderic III succeeded his brother Chlothar III in Neustria in 673, but Childeric II of Austrasia displaced him soon thereafter—until he died in 675, and Theuderic III retook his throne. When Dagobert II died in 679, Theuderic received Austrasia as well and became king of the whole Frankish realm. Thoroughly Neustrian in outlook, he allied with his mayor Berchar and made war on the Austrasian who had installed Dagobert II, Sigebert III's son, in their kingdom (briefly in opposition to Clovis III).

In 687 he was defeated by Pepin of Herstal, the Arnulfing mayor of Austrasia and the real power in that kingdom, at the Battle of Tertry and was forced to accept Pepin as sole mayor and dux et princeps Francorum: "Duke and Prince of the Franks", a title which signifies, to the author of the Liber Historiae Francorum, the beginning of Pepin's "reign". Thereafter the Merovingian monarchs showed only sporadically, in our surviving records, any activities of a non-symbolic and self-willed nature.

During the period of confusion in the 670s and 680s, attempts had been made to re-assert Frankish suzerainty over the Frisians, but to no avail. In 689, however, Pepin launched a campaign of conquest in Western Frisia (Frisia Citerior) and defeated the Frisian king Radbod near Dorestad, an important trading centre. All the land between the Scheldt and the Vlie was incorporated into Francia.

Then, circa 690, Pepin attacked central Frisia and took Utrecht. In 695 Pepin could even sponsor the foundation of the Archdiocese of Utrecht and the beginning of the conversion of the Frisians under Willibrord. However, Eastern Frisia (Frisia Ulterior) remained outside of Frankish suzerainty.

Having achieved great successes against the Frisians, Pepin turned towards the Alemanni. In 709 he launched a war against Willehari, duke of the Ortenau, probably in an effort to force the succession of the young sons of the deceased Gotfrid on the ducal throne. This outside interference led to another war in 712 and the Alemanni were, for the time being, restored to the Frankish fold.

However, in southern Gaul, which was not under Arnulfing influence, the regions were pulling away from the royal court under leaders such as Savaric of Auxerre, Antenor of Provence, and Odo of Aquitaine. The reigns of Clovis IV and Childebert III from 691 until 711 have all the hallmarks of those of rois fainéants, though Childebert is founding making royal judgements against the interests of his supposed masters, the Arnulfings.