Legions were the backbone of the Roman military, playing a crucial role in the expansion and defense of the Roman Empire. Each legion typically consisted of about 5,000 heavily armed infantry soldiers, known as legionaries, along with supporting units such as cavalry and auxiliary troops. The structure of a legion was highly organized, divided into smaller units called cohorts and centuries, which allowed for effective command and flexibility in battle. Roman legions were renowned for their discipline, training, and innovative tactics, contributing to Rome’s dominance over much of Europe, North Africa, and parts of the Middle East. Their legacy is evident in military strategies and formations that continue to influence modern armies today.