In spring an army was assembled at Corinth to prevent the passage of the Thebans and their northern allies into Peloponnesus. But the superior abilities of the Theban leaders prevailed. They surprised an outpost. Doubting still their means for forcing their way over the rough descent of the Onean Mountains, they communicated with the Lacedæmonian polemarch commanding, and, whether through his treachery or his weakness, they obtained a truce, under favour of which they safely joined the forces of their Peloponnesian allies, the Arcadians, Argives, and Eleans. This junction being effected, they found themselves far superior to the army of the Lacedæmonian confederacy. Without opposition then they punished the attachment of the Epidaurians to the Lacedæmonian interest by ravage of their lands. They attempted then one of the gates of Corinth; but, the Corinthians submitting themselves to the able direction of the Athenian general, Chabrias, who was there with a body of mercenaries, they were repulsed with some slaughter. Against so great a superiority of force however the abilities of Chabrias could not prevent the ravage of the Corinthian territory. All Peloponnesus now seemed open to the Thebans, when the pressure of the Thessalian arms, under the tagus, Alexander of Pheræ, upon their northern allies, and apprehension of its extending to Bœotia itself, called the Thebans suddenly out of the peninsula. All the Peloponnesians of the confederacy then, assuming leave of absence, parted to their several homes. The dissolution of the army of the Theban confederacy gave a most fortunate relief to Lacedæmon. All the leisure it afforded seems to have been wanted for composing troubles within Laconia itself. Offensive operations were left to the auxiliaries sent by Dionysius, then ruling in Syracuse; a body remarkable enough, both in itself and for its actions, to deserve notice. The infantry were Gauls and Spaniards; the cavalry, apparently Sicilian Greeks, so excellent that, though scarcely exceeding fifty horsemen, they had given more annoyance to the Thebans, while laying waste the Corinthian lands, than all the rest of the army. After the other troops, on both sides, were withdrawn, this transmarine force alone undertook the invasion of Sicyonia, defeated the Sicyonians in battle, and took a fort in their territory by assault. Gratified then with glory and plunder they embarked, and, with twenty triremes, their convoy, returned to Syracuse.