In the decades after their final victory in the Messenian Wars, the Lacedaemonians turned their attentions eastwards and in the mid-sixth century wrested from Argos the regions lying to the east of Mt. Parnon, the Thyreatis and the Cynuria. The decisive battle was noteworthy for the two sides’ initial use of a specific tactic to minimize casualties, namely the limiting of the actual combatants to a select number, in this case to three hundred from each side. Both sides agreed to abide by the result of the champions’ battle. Unfortunately, that result was itself disputed, and the main armies did meet in a conventional battle which the Lacedaemonians won decisively (Hdt. I 82).
After this battle Argos and Sparta became bitter enemies and remained so, with only brief exceptions, throughout the classical period; and this enmity is an important factor in the various interstate alliances for the next few centuries. Another important result of this battle was Sparta’s acquisition of a port on the Aegean Sea, Prasiae, which lay to the east of Mt. Parnon. Sparta’s chief port in Laconia proper, Gytheium on the Laconian Gulf, could not serve well as an outlet to the Aegean owing to the difficulty of rounding Cape Malea (see Box 1.1). Prasiae therefore was the naval base from which Lacedaemonian fleets set sail during the Peloponnesian and other wars.
At about the same time as the Lacedaemonians conquered the Thyreatis and Cynuria, they also defeated the Arcadian city of Tegea to the north of the Laconian Plain (Hdt. I 67). In this case they declined to annex the territory of Tegea. Neither did they make any attempt to reduce the Tegeates to the status of Helots. Instead they formed an alliance with the Tegeates, the first of a series of alliances which would become the so-called Peloponnesian League.