Why did the Peloponnesian War last so long?
This changed when Persia provided money to Sparta, which was then able to expand its alliance fleet and hire the best sailors, so Athens was matched at sea as well as under seige at home, and unable to collect the tribute from its empire which financed its fleet. Defeat of the Athenian fleet in the Dardanelles ended its naval capability and ability to continue the war.
