An Athenian general incurs Philip's wrath in 341 BCE for operating too near one of his towns in the Chersonese.

Philip demands his recall, but Demosthenes replies in a speech, On the Chersonese, that the motive behind the Macedonian's “scheming and contriving” is to weaken the Athenians' will to oppose Philip's conquests.

“Philip is at war with us,” he declares, “and has broken the peace.” Shortly afterward, Demosthenes delivers his Third Philippic, perhaps the most successful single speech in his long campaign against Philip.

As a result, Demosthenes becomes controller of the navy and can thus carry out the naval reforms he had proposed in 354 BCE.

In addition, a grand alliance is formed against Philip, including Byzantium and former enemies of Athens, such as Thebes.

Indecisive warfare follows, with Athens strong at sea but Philip nearly irresistible on land.

The Macedonian army is well organized under a single brilliant commander who uses cavalry in coordination with highly disciplined infantry, while the Greek alliance depends upon what is essentially a group of citizens' militia.