The Three-Day Reign (1973)

During the last days of the Yi dynasty, conflict arises between the China-leaning conservatives, and the Western-learning and Japan-leaning reformers over how to rule Korea in the future. The reformer Kim Okgyun helps persuade the king to announce Korea's independence, breaking with China. When a conservative agent informs China, Chinese troops enter Korea and end the reign of independence after three days.

Unfortunately the movie The Three-Day Reign is not yet available on HBO Max.