Final answer:
After facing defeat at Aegospotami and the consequent siege, Athens surrendered to Sparta, dismantled its walls, gave up its fleet, and fell under Spartan control, ending the Peloponnesian War.
Step-by-step explanation:
After the Athenians were defeated at the Battle of Aegospotami by the Spartans, Athens was under severe strain and eventually surrendered in 404 BCE, leading to the end of the Peloponnesian War and the collapse of the Athenian empire. Following the surrender, the city had to dismantle its walls and the Long Walls that connected Athens with its port, Piraeus, surrendering its fleet and becoming a member of the Spartan-dominated Peloponnesian League.
However, the Athenians were resilient and within a year they had established a new government, laying the groundwork for a recovery which, although they never regained the power of their heyday, allowed them to remain a significant cultural and intellectual center in the ancient world.
As a result, the city surrendered to Sparta in 404 BCE, marking the end of the Peloponnesian War and the collapse of the Athenian empire.