The peloponnesian war was a particularly hopeless struggle because:

The Peloponnesian war ran for 27 years between the Athenian empire and the Peloponnesian League led by Sparta 431 to 404 BCE. It was a particularly hopeless struggle because neither Sparta nor Athens had sufficient money to finance military forces and continue war. In the war, Athens lost and was stripped of its empire, and became a second rate power in the Greek world.