Meanwhile, on the strength of the dismay caused by his successes, Cleomenes was making an unopposed progress through the cities, winning some by persuasion and others by threats. In this way, he got possession of Caphyae, Pellene, Pheneus, Argos, Phlius, Cleonae, Epidaurus, Hermione, Troezen, and last of all Corinth, while he personally commanded a siege of Sicyon. But this in reality relieved the Achaeans from a very grave difficulty. For the Corinthians by ordering Aratus, as Strategus of the league, and the Achaeans to evacuate the town, and by sending messages to Cleomenes inviting his presence, gave the Achaeans a ground of action and a reasonable pretext for moving. Aratus was quick to take advantage of this; and, as the Achaeans were in actual possession of the Acrocorinthus, he made his peace with the royal family of Macedonia by offering it to Antigonus; and at the same time gave thus a sufficient guarantee for friendship in the future, and further secured Antigonus a base of operations for the war with Sparta. Upon learning of this compact between the league and Antigonus, Cleomenes raised the siege of Sicyon and pitched his camp near the Isthmus; and, having thrown up a line of fortification uniting the Acrocorinthus with the mountain called the “Ass’s Back,” began from this time to expect with confidence the empire of the Peloponnese. But Antigonus had made his preparations long in advance, in accordance with the suggestion of Aratus, and was only waiting for the right moment to act. And now the news which he received convinced him that the entrance of Cleomenes into Thessaly, at the head of an army, was only a question of a very few days: he accordingly despatched envoys to Aratus and the league to conclude the terms of the treaty and marched to the Isthmus with his army by way of Euboea. He took this route because the Aetolians, after trying other expedients for preventing Antigonus bringing this aid, now forbade his marching south of Thermopylae with an army, threatening that, if he did, they would offer armed opposition to his passage.