Persia.
yes it did.
No, Sparta was not part of the Delian League. The Delian League was a coalition of Greek city-states led by Athens, formed in 478 BCE to continue the fight against Persia after the Persian Wars. Sparta, on the other hand, was a member of the Peloponnesian League, which was a rival alliance to the Delian League. The two leagues eventually clashed in the Peloponnesian War.
They enabled Athens to establish an empire from the Delian League which it formed to oppose the Persians. This empire became involved in the Peloponnesian War after peace was made by Persia and Athens used the Delian League to promote its own interests against othe Greek cities of the Peloponnesian League. Persia helped the Peloponnesian League to defeat Athens.
Initially, yes. Later it was more of a vehicle for Athenian imperialism.
The Athenian Soldiers
Sparta led the Peloponnesian League, Athens led the Delian League.
No, they were defeated by Sparta and it's allies. The Delian League was formed to defend against Persia, and after peace was made with the Persian Empire, it was turned by Athens into an empire of its own. Athens used its resources of the old League to war against the Peloponnesian League led by Sparta.
Delian League, mostly Greek cities of Asia Minor and the Islands, converted to the Athenian empire after peace with Persia. Peloponnesian League led by Sparta, mainly Dorian Greek cities of Peloponnesian peninsula of southern Greece.
Delian league
After the Persian threat subsided, he converted the Delian League, which was formed to oppose Persia, into an empire of Athens, giving Athens the resources of over 189 city-states.
It converted the Delian League which it had led against Persia in the later stages of the war into an empire of its own, and began interfering in the other cities, leading to the devastating Peloponnesian War.