The battle was a battle between the Macedonian and the Athenian coallition and all of them were Greeks.
Alexander the Great, addressing the dead Greeks of the Battle of Chaeronea:
"Holy shadows of the dead, Im not to blame for your cruel and bitter fate, but the accursed rivalry which brought sister nations and brother people, to fight one another."...
..."I do not feel happy for this victory of mine. On the contrary, I would be glad, brothers, if I had all of you standing here next to me, since we are united by the same language, the same blood and the same visions."
(Historiae Alexandri Magni, 6.3.11, by Roman historian Quintus Curtius Rufus)
In ancient China, the Qin dynasty united all the other Chinese kingdoms through war and thus creating the Chinese empire. The same thing Philip did in Chaeronia.
The same did Attila to unite the Huns.