Hoplites were well-trained citizen-soldiers of ancient Greece. Armed with spears and durable armor, they fulfilled the heavy infantry role in most engagements. Hoplites will always be associated with the phalanx unit formation. This tactic involved tightly packed groupings of eight or 16 rows of soldiers, who, against other citizen-soldiers, move and attack in unison scattering less densely organized enemy forces. This tactic worked well, but broke down when facing more mobile and well-trained professional soldiers. The Roman legions victory over the Macedonian phalanx at Pydna in 168 BC effectively ended the Hoplite's battlefield usefulness.