Rise of the Greek Hoplite Phalanx
Greek city-states developed the hoplite phalanx, a close-order infantry formation of citizens who bought their own armor and fought as equals in the line. Hoplite service tied military duty to citizenship: the man who could afford arms had a stake in, and a voice in, the polis. This citizen-soldier model shaped Greek political life and became a reference point for later ideas about who has the right and duty to fight.