Plutarch, Aratus
Bernadotte Perrin, Ed.

35. And now Aratus, seeking to effect his long-standing purpose, and impatient of the tyranny so near the Achaeans in Argos, sent messengers and tried to persuade Aristomachus to give his city freedom and attach it to the Achaean League, urging him to imitate Lydiades and be general of so great a nation with praise and honour, rather than tyrant of a single city with peril and hatred. [2] Aristomachus consented, and told Aratus to send him fifty talents, in order that he might disband and send away the soldiers under him, and the money was being provided. Upon this, Lydiades, who was still general and had an ambition that the Achaeans should regard this transaction as his own work, denounced Aratus to Aristomachus as a man who had always been an implacable enemy of tyrants, and after persuading Aristomachus to entrust the matter to himself, brought him before the Achaean council. [3] Then the members of the council put into clearest light their goodwill towards Aratus and their confidence in him. For when he angrily opposed the project, they drove Aristomachus away; but when he had been won over again, and came before them in person, and began to argue for the project, they speedily and readily adopted all his proposals, admitted Argos and Phlius into the league, and a year later¹ actually choose Aristomachus general.

[4] Aristomachus, then, being in high favour with the Achaeans, and wishing to invade Laconia, summoned Aratus from Athens. Aratus wrote him a letter in which he tried to dissuade him from the expedition, and expressed unwillingness to involve the Achaeans in hostilities with Cleomenes, who was daring and growing marvellously in power; but, since Aristomachus was altogether insistent, Aratus obeyed orders and accompanied the expedition in person. [5] It was at this time that he prevented Aristomachus from joining battle when Cleomenes came upon them at Pallantium,² and was denounced therefore by Lydiades, with whom he came into contest and competition for the office of general, winning the vote and being chosen general for the twelfth time.