The Spartans were highly disliked for their arrogance, but they were highly respected and admired for their army's fighting prowess. As a result, when the Persians first invaded, the Spartans were the first people who were looked to to provide a defense. (5)

However, by the end of the Persian Wars, when Athens had assumed leadership of the Greek alliance, the Spartans withdrew back to their city. While the Athenians were winning allies that lived by the sea, those city-states that were land-locked allied with Sparta. Sparta was thus able to increase their power in a similar way to Athens.(1)

As time progressed, Athens began to dominate the Delian league and took advantage of its allies' desire to stop sending ships and men. As a result, the members of the Delian league contributed money to the league rather than ships.

In time, the alliance between Sparta and the other city-states on the Peloponneses became known as the Peloponnesian League. This alliance was essentially formed to counter the Delian League, which Sparta and the land-bound city-states considered a threat. Sparta became the clear leader of this alliance, and stood opposite Athens as one of the great powers of Greece.(6)