Strabo Geography 8.7.3

[3] The Achaeans, during a period of five and twenty years, elected, annually, a common secretary, and two military chiefs. Their common assembly of the council met at one place, called Arnarium, (Homarium, or Amarium,) where these persons, and, before their time, the Ionians, consulted on public affairs. They afterwards resolved to elect one military chief. When Aratus held this post, he took the Acrocorinthus from Antigonus, and annexed the city as well as his own country to the Achaean league. ¹ He admitted the Megareans also into the body, and, having destroyed the tyrannical governments in each state, he made them members, after they were restored to liberty, of the Achaean league. * * * * * He freed, in a short time, Peloponnesus from the existing tyrannies; thus Argos, Hermion, Phlius, and Megalopolis, the largest of the Arcadian cities, were added to the Achaean body, when they attained their greatest increase of numbers. It was at this time that the Romans, having expelled the Carthaginians from Sicily, undertook an expedition against the Galatae, who were settled about the Po. ² The Achaeans remained firmly united until Philopoemen had the military command, but their union was gradually dissolved, after the Romans had obtained possession of the whole of Greece. The Romans did not treat each state in the same manner, but permitted some to retain their own form of government, and dissolved that of others. * * * * * [He then assigns reasons for expatiating on the subject of the Achaeans, namely, their attainment of such a degree of power as to be superior to the Lacedaemonians, and because they were not as well known as they deserved to be from their importance.] ³