allied herself with Athens, allowing construction of a double line of walls across the Isthmus of Corinth and protecting Athens from attack from that quarter. Roughly a decade earlier, due to encouragement from influential speaker Themistocles, the Athenians had also constructed the Long Walls connecting their city to the Piraeus, its port, making it effectively invulnerable to attack by land. In 454 BC, the Athenian general Pericles moved the Delian League's treasury from Delos to Athens, allegedly to keep it safe from Persia. However, Plutarch indicates that many of Pericles's rivals viewed the transfer to Athens as usurping monetary resources to fund elaborate building projects. Athens also switched from accepting ships, men and weapons as dues from league members, to only accepting money. The new treasury established in Athens was used for many purposes, not all relating to the defence of members of the league. It was from tribute paid to the league that Pericles set to building the Parthenon on the Acropolis, replacing an older temple, as well as many other non-defense related expenditures. The Delian League was turning from an alliance into an empire. Wars against Persia War with the Persians continued. In 460 BC, Egypt revolted under local leaders the Hellenes called Inaros and Amyrtaeus, who requested aid from Athens. Pericles led 250 ships, intended to attack Cyprus, to their aid because it would further damage Persia. After four years, however, the Egyptian rebellion was defeated by the Achaemenid general Megabyzus, who captured the greater part of the Athenian forces. In fact, according to Isocrates, the Athenians and their allies lost some 20,000 men in the expedition, while modern estimates place the figure at 50,000 men and 250 ships including reinforcements. The remainder escaped to Cyrene and thence returned home. This was the Athenians' main (public) reason for moving the treasury of the League from Delos to Athens, further consolidating their control over the League. The Persians followed up their victory by sending a fleet to re-establish their control over Cyprus, and 200 ships were sent out to counter them under Cimon, who returned from ostracism in 451 BC. He died during the blockade of Citium, though the fleet won a double victory by land and sea over the Persians off Salamis, Cyprus. This battle was the last major one fought against the Persians. Many writers report that a peace treaty, known as the Peace of Callias,