Plutarch, Aratus
Bernadotte Perrin, Ed.

16. Aratus now, having been chosen general of the Achaean League for the first time, ravaged the opposite territories of Locris and Calydonia, and went to the assistance of the Boeotians with an army of ten thousand men. He came too late, however, for the battle at Chaeroneia, in which the Boeotians were defeated by the Aetolians, with the loss of Aboeocritus, their Boeotarch, and a thousand men. [2] A year later,¹ being general again, he set on foot the enterprise for the recovery of Acrocorinthus, not in the interests of Sicyonians or Achaeans merely, but purposing to drive from that stronghold what held all Hellas in a common subjection,—the Macedonian garrison. [3] Chares the Athenian, having been successful in a battle with the king's generals, wrote to the people of Athens that he had won a battle which was ‘sister to that at Marathon’; and this enterprise of Aratus may be rightly called a sister of those of Pelopidas the Theban and Thrasybulus the Athenian, in which they slew tyrants, except that it surpassed them in being undertaken, not against Greeks, but against a foreign and alien power. [4] For the Isthmus of Corinth, forming a barrier between the seas, brings together the two regions, and thus unites our continent; and when Acrocorinthus, which is a lofty hill springing up at this centre of Greece, is held by a garrison, it hinders and cuts off all the country south of the Isthmus from intercourse, transits, and the carrying on of military expeditions by land and sea, [5] and makes him who controls the place with a garrison sole lord of Greece. Therefore it is thought that the younger Philip of Macedon² uttered no jest, but the truth, whenever he called the city of Corinth ‘the fetters of Greece.’