Passage 7.8.3
Κορίνθιοι δὲ ἀπὸ Μακεδόνων ἐλευθερωθέντες μετέσχον αὐτίκα συνεδρίου τοῦ Ἀχαιῶν, μετασχόντες καὶ πρότερον, ὅτε Ἄρατος καὶ Σικυώνιοι φρουρὰν ἐκ τοῦ Ἀκροκορίνθου τὴν πᾶσαν ἐξήλασαν καὶ ἀπέκτειναν Περσαῖον ὑπὸ Ἀντιγόνου ταχθέντα ἐπὶ τῇ φρουρᾷ. Ἀχαιοὶ δὲ τὸ ἀπὸ τούτου σύμμαχοί τε ὠνομάζοντο Ῥωμαίων καὶ ἐς τὰ πάντα ἦσαν πρόθυμοι· καί σφισιν εἵποντο μὲν ἐς Μακεδονίαν καὶ ἐπὶ Φίλιππον, μετέσχον δὲ καὶ στρατείας ἐς Αἰτωλούς, τρίτα δὲ ὁμοῦ Ῥωμαίοις ἐμαχέσαντο ἐναντία Ἀντιόχου καὶ Σύρων.
The Corinthians, having been freed from the Macedonians, immediately joined the federation of the Achaeans. They had previously participated as well, at the time when Aratus and the Sicyonians drove out the entire garrison from Acrocorinth and killed Persaeus, whom Antigonus had appointed governor of the fortress. From this point forward the Achaeans were called allies of the Romans and were enthusiastic in every respect. They followed them into Macedonia against Philip, took part in the campaign against the Aetolians, and thirdly, fought alongside the Romans against Antiochus and the Syrians.