 Callias of Chalcis now emerged as a potential ally of the Athenians; still intent on unifying the cities of Euboea under his leadership, he had been disturbed by the number of Euboean cities, particularly Eretrea and Oreus, adopting a pro-Macedonian stance.In June 341 BC, Athens and Chalcis allied themselves, and proceeded to attack Eritrea and Oreus and install suitable governance in those cities.Callias then proceeded to harass the cities and shipping on the Gulf of Pagasae.