I think it's whom because it makes more scenes that way.
Andrew Jackson made the Cherokees march about 2,200 miles west to their new territory, after kicking them out of their own land and claiming it as hid own. Even women and children had to walk, while his men led them on horses.
China had invaded Vietnam
Sparta was ruled by two kings, who ruled until they died or were forced out of office. Athens was ruled by archons, who were elected annually. Thus, because both parts of Athens' government had leaders who were elected, Athens is said to have been the birthplace of democracy. Spartan life was simple.