The document discusses the traditional battle formations used in ancient warfare and the development of the hoplite phalanx formation by the Greeks in 650 BCE. It describes how the Greeks trained soldiers to fight shoulder to shoulder in tight lines, using their shields to protect each other. This allowed them to march forward together effectively. It also discusses how discipline and training were needed to maintain the formation's integrity under pressure. The hoplite phalanx helped Greece fight off the Persians during battles in the Persian Wars in the early 5th century BCE, including Marathon, Thermopylae, Salamis, and Plataea.