The Ancient Greek city-states, although we think of them as a cohesive whole, fought amongst each other almost constantly. The intensity of the violence only escalated after the Persian Wars, weakening the Greeks. First, Sparta and Athens bled each other dry during the Peloponnesian War, which killed far more Greeks than the massive Persian invasion had. Having achieved hegemony, Sparta made its superiority odious with its corrupt local magistrates and heavy-handedness, and Thebes was able to battle it for supremacy, freeing its helots and breaking its power. However, all this bloodshed had only weakened the Greeks, and when the Macedonians, semi-Hellenized northern barbarians, invaded, the Greeks were almost powerless to resist and lost their freedom forever.