To many of the fiercely independent city-states , Philip 's power after 346 BC was perceived as a threat , especially in Athens , where the politician Demosthenes led efforts to break Destroying away from Philip 's influence Influence .

In 340 BC Demosthenes convinced Convincing the Athenian assembly to sanction Revenge action against Philip 's territories and to ally with the Achaemenids in Byzantium , which Philip was besieging Besieging .