History of the Peloponnesian War

The Lacedaemonians, on the other hand, when their war with the rebels on Ithome proved a long affair, appealed to their allies in general and especially to the Athenians, who came with a considerable force under the command of Cimon.

The principal reason why an appeal was made to them was that they were reputed to be skilful in siege operations, whereas the long continuance of the siege showed their own deficiency in this respect; for otherwise they would have taken the place by assault.

And it was in consequence of this expedition that a lack of harmony in the relations of the Lacedaemonians and the Athenians first became manifest. For the Lacedaemonians, when they failed to take the place by storm, fearing the audacity and the fickleness of the Athenians, whom they regarded, besides, as men of another race, thought that, if they remained, they might be persuaded by the rebels on Ithome to change sides; they therefore dismissed them, alone of the allies, without giving any indication of their suspicion, but merely saying that they had no further need of them.

The Athenians, however, recognized that they were not being sent away on the more creditable ground, but because some suspicion had arisen; so because they felt indignant and considered that they had not deserved such treatment at the hands of the Lacedaemonians, the instant they returned home they gave up the alliance which they had made with the Lacedaemonians against the Persians and became allies of their enemies, the Argives. And an alliance at the same time, on the same terms and confirmed by the same oaths, was concluded by both the Athenians and the Argives with the Thessalians.