Childeric III died in 754.
Childeric III was born in 717.
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.
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.
300 Bees in the Tomb of Childeric
Shapur III died in 388.
Amoghavarsha III died in 939.
Dagobert III died in 715.
Yazid III died in 744.
Arshak III died in 389.
Hamengkubuwono III died in 1814.