The route by sea, across the Crissaean gulf, exposed them to the risk of being stopped by the Athenian fleet; that across Geraneia seemed scarcely safe, the Athenians holding Megara and Pegae. For the pass was a difficult one, and was always guarded by the Athenians; and, in the present instance, the Lacedaemonians had information that they meant to dispute their passage.

So they resolved to remain in Boeotia, and to consider which would be the safest line of march. They had also another reason for this resolve. Secret encouragement had been given them by a party in Athens, who hoped to put an end to the reign of democracy and the building of the long walls.

Meanwhile the Athenians marched against them with their whole levy and a thousand Argives and the respective contingents of the rest of their allies. Altogether they were fourteen thousand strong.

The march was prompted by the notion that the Lacedaemonians were at a loss how to effect their passage, and also by suspicions of an attempt to overthrow the democracy.

Some cavalry also joined the Athenians from their Thessalian allies; but these went over to the Lacedaemonians during the battle.