In modern day history Japan, Jimmu’s Ascension marked the first day of Japan’s National foundation day #onthisday on February 11th.
Emperor Jimmu was the first Emperor of Japan according to the local legend. His traditional date of taking the throne was 660 B.C.
In Japanese mythology he was a descendant to the Sun goddess, Amaterasu. He went on a military expedition of Hyuga and then near the Inland Sea he captured Yamato which he had established as his centre of power.