Final answer:
Sparta made an agreement with Persia to fund their navy in the Peloponnesian War.
Step-by-step explanation:
Sparta made an agreement with Persia to fund their navy. The Spartans realized they needed a large fleet to defeat Athens, and Persia agreed to provide funds on the condition that Sparta restore the Greek cities in Ionia to Persian rule. This agreement allowed Sparta to secure the necessary resources for their navy, leading to their eventual victory over Athens in the Peloponnesian War.