In ancient times, drilling increased in importance when men stopped fighting as individuals and began to fight together as units. Drilling as a vital component of a war machine further increased with the increases in the size of armies, for example, when Phillip II of Macedon disciplined his army so they could swiftly form the phalanxes that were so critical to his successes as a general. Military drilling later was used by the Roman Army to maximise efficiency and deadliness throughout their long history. After the fall of the empire, the Dark Ages set in Europe, most feudal lords more heavily relied on peasant levies and their wealthy knights to fight their wars, the knights, for the most part, reverting to fighting as individuals. Massed military drilling was used mostly by only the foremost armies and nations, such as the Normans.