One thing was strife between the city-states. This continued on after the persian wars.
First Athens, then Sparta, then Thebes until Macedonia took over.
Athens.
The Athens emerged as the most powerful city-state in Greece.
The Delian League led by Athens and the Peloponnesian League led by Athens.
No one. Athens organised its empire in the aftermath of the Persian invasion. Sparta minded its own business. None of the other city-states were in a position to dominate anyone.
It became a standoff between Athens and its empire and Sparta and its allies, leading to a resolution in the destructive Peloponnesian War.
No, Ancient Greece was not a city state. city sates were part of Greece
No, Greece is neither a city or a state.
There were two opposing power blocs - the Athenian empire and the Peloponnesian League led by Sparta. After the Peloponnesian War between the two when Athens lost, Sparta dominated temporarily for three decades until beaten and replaced by Thebes.
The city that was the head of the Delian League was Athens, Greece.
The first Persian invasion of Greece was during the Persian Wars in 492 BCE. It was ordered by the Persian King Darius I to punish the city-states of Athens and Eretria.