Childeric III was born in 717.
Childeric III died in 754.
Childeric II died in 675.
Childeric II was born in 653.
Childeric I or Clovis I. Childeric can be considered the first king, but Clovis conquered much of the territory owned by the Merovingians.
300 Bees in the Tomb of Childeric
Nothing special happened to Rome in 750 CE. The pope was Zachary, who was the Bishop of Rome form 741 to 752 . He encouraged the deposition of the last Merovingian king of the Franks Childeric III and Pepin (the initiator of the Carolingian dynasty) to become king. Childeric III was deposed on 752. If you are referring to 750 BCE, 753 BCE was the date of the foundation of Rome.
Amoghavarsha III was born in 934.
Dagobert III was born in 699.
Hamengkubuwono III was born in 1812.
Indra III was born in 914.
Narasimha III was born in 1254.
Ardashir III was born in 621.