The latter were now in serious embarrassment. Not having executed their portion of the treaty, they could not demand that Athens should execute hers: and they were threatened with the double misfortune of forfeiting the confidence of their allies without acquiring any one of the advantages of the treaty. In this dilemma they determined to enter into closer relations, and separate relations, with Athens, at all hazard of offending their allies. Of the enmity of Argos, if unaided by Athens, they had little apprehension; while the moment was now favorable for alliance with Athens, from the decided pacific tendencies reigning on both sides, as well as from the known philo-Laconian sentiment of the leaders Nikias and Lachês. The Athenian envoys had remained at Sparta ever since the swearing of the peace, awaiting the fulfilment of the conditions; Nikias or Lachês, one or both, being very probably among them. When they saw that Sparta was unable to fulfil her bond, so that the treaty seemed likely to be cancelled, they would doubtless encourage, and perhaps may even have suggested, the idea of a separate alliance between Sparta and Athens, as the only expedient for covering the deficiency; promising that under that alliance the Spartan captives should be restored. Accordingly, a treaty was concluded between the two, for fifty years; not merely of peace, but of defensive alliance. Each party pledged itself to assist in repelling any invaders of the territory of the other, to treat them as enemies, and not to conclude peace with them without the consent of the other. This was the single provision of the alliance, with one addition, however, of no mean importance, for the security of Lacedæmon. The Athenians engaged to lend their best and most energetic aid in putting down any rising of the Helots which might occur in Laconia. Such a provision indicates powerfully the uneasiness felt by the Lacedæmonians respecting their serf-population: but at the present moment it was of peculiar value to them, since it bound the Athenians to restrain, if not to withdraw, the Messenian garrison of Pylos, planted there by themselves for the express purpose of provoking the Helots to revolt. An alliance with stipulations so few and simple took no long time to discuss. It was concluded very speedily after the return of the envoys from Amphipolis, probably not more than a month or two after the former peace. It was sworn to by the same individuals on both sides; with similar declaration that the oath should be annually renewed, and also with similar proviso that Sparta and Athens might by mutual consent either enlarge or contract the terms, without violating the oath.[6] Moreover, the treaty was directed to be inscribed on two columns: one to be set up in the temple of Apollo at Amyklæ, the other in the temple of Athênê, in the acropolis of Athens.