Hirohito conducts Japanese troop review during World War II

During World War II, Japanese soldiers viewed Emperor Hirohito as a divine figure, embodying a god in human form. This belief granted him the authority to demand any sacrifice from his followers, regardless of the cost. The Emperor, symbolized as the ruler on the White Horse, held absolute power over his subjects, who demonstrated extreme devotion and willingness to sacrifice in his name.

In what way did the ruler on the White Horse hold the lives of his subjects?

What does the phrase 'fanatical heights of endeavor' imply about the devotion of the subjects?