Philip II of Macedon
It was Philip the second who finally managed to achieve this objective. In a time of shifting powers when the other major greek states were weak, Philip managed to unify Macedonia through diplomacy, bribery and an increased importance in the military. Within a year of his succession he had managed to raise an army of ten thousand and begun a radical re-organisation of how it trained and fought. This had the effect of stabilising the country because now the peasants loyalty to the nobles was weakened as they were now directly serving the king. The nobles themselves were bound to the king by becoming the kings 'Companions', and their superior cavalry were put to good use as the royal bodyguard. All these changes turned Macedonia into a highly efficient armed state, allowing it to secure its borders and force treaties with the other greek factions.
Ultimately it was Philips legacy that enabled his son Alexander the Great to carve his way into the history books as he led the Macedonian army to conquer the Persian Empire.
Here are some ideas and sketches i've been preparing to help me design the character.