The phalanx was a key military formation in ancient Greek warfare characterized by a tight infantry formation where soldiers, known as hoplites, stood shoulder to shoulder in rows. This strategy enhanced their strength and cohesion in battle, allowing them to push forward as a unified front. The effectiveness of the phalanx laid the groundwork for many battlefield tactics employed by Greek city-states, particularly during the Persian Wars. Its success highlighted the importance of discipline and teamwork in military engagements and influenced military strategies for centuries.