After this the Athenians marched to Plataea and brought in provisions, and left a garrison in the place, also taking away the women and children and such of the men as were least efficient.
After the affair at Plataea, the treaty had been broken by an overt act, and Athens at once prepared for war, as did also Lacedaemon and her allies.

They resolved to send embassies to the King and to such other of the barbarian powers as either party could look to for assistance, and tried to ally themselves with the independent states at home.
Lacedaemon, in addition to the existing marine, gave orders to the states that had declared for her in Italy and Sicily to build vessels up to a grand total of five hundred, the quota of each city being determined by its size, and also to provide a specified sum of money.
Till these were ready they were to remain neutral and to admit single Athenian ships into their harbours.

Athens on her part reviewed her existing confederacy, and sent embassies to the places more immediately round Peloponnese--Corcyra, Cephallenia, Acarnania, and Zacynthus--perceiving that if these could be relied on she could carry the war all round Peloponnese.
And if both sides nourished the boldest hopes and put forth their utmost strength for the war, this was only natural.

Zeal is always at its height at the commencement of an undertaking; and on this particular occasion Peloponnese and Athens were both full of young men whose inexperience made them eager to take up arms, while the rest of Hellas stood straining with excitement at the conflict of its leading cities.
Everywhere predictions were being recited and oracles being chanted by such persons as collect them, and this not only in the contending cities.

Further, some while before this, there was an earthquake at Delos, for the first time in the memory of the Hellenes.