Usage patterns
〈人〉が君主として即位するfor someone to ascend the throne as monarch
He ascended the throne as monarch at a young age.
君主が〈場所〉を統治するfor a monarch to rule over a place/country
That monarch has ruled the country for many years.
君主を廃するto depose/abolish a monarch
The monarch was deposed as a result of the revolution.
