Heavy infantry refers to a class of foot soldiers trained and equipped to fight in close combat, typically wearing substantial armor and carrying heavy weapons. Historically, heavy infantry units were distinguished from light infantry by their emphasis on protection, formation-based tactics, and use in frontal engagements. They were often deployed as the main fighting force in armies of antiquity and the medieval period.
In ancient warfare, examples include the Greek hoplites, who fought in a phalanx formation using large shields (aspides), spears, and bronze armor, and the Roman legionaries, who were equipped with helmets, mail or plate armor, shields (scuta), and short swords (gladii). These troops were designed for sustained combat and were capable of maintaining disciplined formations under pressure.
During the medieval and early modern periods, heavy infantry evolved with advancements in weaponry and armor. Units such as the Swiss pikemen and later tercios of the Spanish army combined heavy armor with long pikes and early firearms. Over time, the development of gunpowder weapons and changes in battlefield tactics led to a decline in heavy armor, though the role of disciplined infantry remained central.
In modern military contexts, the distinction between heavy and light infantry is often based on mission, mobility, and equipment rather than personal armor. "Heavy infantry" is not commonly used as an official designation, but the term may informally describe infantry supported by armored vehicles or operating in conjunction with mechanized or armored units.
Accurate information is not confirmed regarding the continued formal use of the term "heavy infantry" in contemporary military doctrine.