Long Walls
In the second phase of the war, the walls again became central to the strategy of both sides. The Spartans occupied a fort at Decelea in Attica in 413 BC, and placed a force there that posed a year-round threat to Athens. In the face of this army, the Athenians could only supply the city by sea. Athens was also weakened from the disastrous conclusion of the Sicilian Expedition and began to modify their walls in the summer of 413 BC and ultimately abandoned the Athens-Phaleron Wall, focusing on the two Piraeus Walls. The Long Walls, and the access to a port that they provided, were by now the only thing protecting Athens from defeat. Realizing that they could not defeat the Athenians on land alone, the Spartans turned their attention to constructing a navy, and throughout the final phase of the war devoted themselves to trying to defeat the Athenians at sea. Their eventual success, Aegospotami, cut the Athenians off from their supply routes and forced them to surrender. One of the most important terms of this surrender was the destruction of the long walls which were dismantled in 404 BC. The peace treaty that was reached in the same year also provided the termination of Athens' naval power. Xenophon tells us that the long walls were torn down with much jubilation and to the song of flute girls.