But no sooner was this begun than a protest arose from rival states. The Spartans in particular raised such a clamor on the subject that Themistocles went to that city and denied that he was fortifying Athens. If they did not believe him, they might send there and see. They did so, and the Spartan ambassadors, on arriving there, found the walls completed and themselves held as hostages for the safe return of Themistocles. Not only Athens was thus fortified, but a still stronger wall was built around Piraeus, the port, four miles away. Years afterwards, when Athens was in a position to defy the protest of Sparta, her famous Long Walls were built, extending from the city to the port, and forming a great artery through which the food and products brought in ships from distant lands could flow to the city from the sea, in defiance of foes. These walls it was that enabled Athens to survive and flourish when all the soil of Attica lay in the hands of the Spartan enemy. But the time came when these walls were to fall, and Athens to lie helpless in the hands of her mortal foe. The Peloponnesian war was full of incident, victories and defeats, marches and countermarches, making and breaking of truces, loss of provinces and fleets, triumphs of one side and the other, and still the years rolled on, and neither party became supreme. Athens had its ill-advisers, who kept it at war when it could have won far more by concluding peace, and who induced it to forget the advice of Pericles and make war on land when its great strength lay in its fleet. Its great error, however, was an attempt at foreign conquest, when it had quite enough to occupy it at home. War broke out between Athens and Sicily, and a strong fleet was sent to blockade and seek to capture the city of Syracuse. This expedition fatally sapped the strength of the Athenian empire. Ships and men were supplied in profusion to take part in a series of military blunders, of which the last were irreparable. The fleet, with all on board, was finally blocked up in the harbor of Syracuse, defeated in battle, and forced to yield, while of forty thousand Athenian troops but a miserable remnant survived to end their lives as slaves in Syracusan quarries. It was a disaster such as Athens in its whole career had not endured, and whose consequences were inevitable. From that time on the supremacy of Athens was at an end.