E.C. Marchant, Commentary on Thucydides: Book 3

Ἀμπρακιῶται—Amphilochian Argos now belonged to Amphilochians and Acarnanians. But the Ambraciots, who had once possessed it, and had been turned out by the help of Athens, in 437 B.C., wanted to recover it. They had made a vain attempt to do so in 430 B.C. The Ambraciots were in alliance with Sparta.

πᾶν τὸ ἠπειρωτικόν—cf. c. 94, 3. In 429 B.C. the Ambraciots had held out hopes to Sparta of acquiring (1) Acarnania (2) Zacynthus and Cephallenia, (3) Naupactus. It is noteworthy that nothing is said this time about the islands, doubtless because the crushing naval defeats the Peloponnesians had sustained from Phormio in 429 and their rough experiences again during the troubles in Corcyra made any project for the acquisition of these islands hopeless. Since the latter events, it is hardly surprising that Athens did not trouble to acquire Leucas (see c. 94, 2).