The ways that the continued battles between the city-states after the Peloponnesian War weakened the city-states include:
Fall of Athens
Foreign attacks.
<h3>What was the Peloponnesian War?</h3>
The Peloponnesian War was the long battle fought for military supremacy between Athens and Sparta between 431 and 404BC.
The Peloponnesian War marked:
The end of the Golden Age of Greece.
A change in styles of warfare
The fall of Athens.
The absorption of Athens into the Spartan Empire.
Thus, the continued battles between the city-states after the Peloponnesian War weakened the city-states and left them vulnerable to foreign invasion because Athens fell from its commanding heights.