Infantry Infantry are groups of soldiers that fights on foot , consisting of soldiers who can fight in all types of terrain and under any weather conditions and can use various means of transport to be brought to the front . Its main mission is to seize and hold ground , taking advantage of the ability to progress in small fractions of highly mobile and difficult to detect . The infantry often employs contemporary pricípio of fire and movement to achieve a dominant position in relation to that of the enemy . The modern Infantry follows an organization that divides the infantry grouped into units called division s , brigade s , battallion s , companies , platoon s and Corps . History . The infantry with their soldiers , known as infants , since antiquity , have always been the main force fighting in an army . A notable exception was the nomadic societies , like the Huns or Mongols , who basically fought with soldiers riding on Cavalry . In the ancient age the most known armies were the Greek and Roman soldiers , who fought in compact groups , armed with swords and spears and protected by metal armor and helmets . The Roman Legion perfected the organization of infantry units and subunits , which today is based on the organization of modern armies . A legion was divided into ten cohort s , in turn divided into a variable number of centuries , which were composed of about a hundred men each . In total , vary depending on the historical period , the Roman legion could be between 3 to 6 thousand men . With the advent of firearms , in the late Medieval age , infantry came to have tactical organization and different job , being employed in solid lines shooters , side by side that went against the other line , in front of the enemy . As the weapons of the era , musket s and arquebus es had a very slow rate of fire , shooters were complemented by other troops armed with swords or long spears called pike s . Over time the guns were being improved and the pikemen were gradually disappearing , and that its role was replaced by the Bayonet , a sharp blade that is fitted to the mouth of the rifle and is used if the soldier needs to proceed to a hand to hand combat . The evolution and increasing the capacity of firearms has led the infantry ceased to be employed in the firing line . The development of artillery in the nineteenth century , when the guns started to have longer range and greater rate of fire , also contributed to the use of infantry was changed . In the American Civil War , the Paraguayan War and the Franco - Prussian War , the infantry began to act only in line and began to dig trench es for protection . The World War I became known as the " war of the trenches " for the greater firepower of artillery and machine guns blocked the movement of infantry . Although , during the World War II , the tanks of the cavalry came to have a role in the great offensive , the infantry was still the most numerous weapons and responsible for the maintenance and occupancy of the land taken from the enemy . When being transported in vehicles , it became known as motorized or mechanized infantry . A specialized form of the infantry is the Marine , whose transport is done by sea in ships of war , especially prepared for the landing , and amphibian cars that can go from sea to land directly in combat conditions . Uniform . At the classic znd medieval age the uniforms of infantry were metal armour s with helmet s and shield s , the last could be made of metal ( like the greek hoplite s bronze shields ) or wood ( like the roman Hastati tower shields ) this only not ocurred on Japan where the Samurai did not used shields . Richer soldiers and officers used richly ornated armours , this was the common style of " uniform " until the gunpowder age At the time of the Napoleonic Wars from 1769 to 1821 , the soldiers had uniforms flashy and colorful as the clothes of the nobles of fashion to be recognized by peers and distinguish the enemy in the confusion of the battlefield . With the passage of time and the evolution of techniques and weapons of war became the uniform color that confused with the surrounding environment , which became known as camouflage uniform . Organization . The Infantry is notable for its reliance on organized formations . These have been developed over time , but still the key player in the employment of Infantry . By the twentieth century Infantry units were mostly used in closed formations until the last moment . These were necessary to allow commanders to maintain control of the unit , especially during the maneuver , as well as the officers could maintain discipline in the ranks . With the development of weapons with greater firepower , it was necessary to disperse the infantry on the ground . This made the units less vulnerable to weapons fire faster and more explosive power . Since World War I came to the conclusion that the infantry would be used more successfully taking advantage of its ability to maneuver in restricted terrain and their ability to avoid detection , something impossible for other troops , like cavalry . The decentralization of command was made possible through the improvement of communications equipment and greater focus on training small units . Mission . The most important function of the infantry has been as a primary force of an army . It is the infantry that ultimately decides whether the land was taken and it is their presence that ensures control of the territory . While the tactics of employment were changed , the basic mission of the infantry was not . Attack is the most basic operation of the Infantry and , along with defense , form one of two primary missions of the infantry on the battlefield . Traditionally , in a confrontation in the open , two armies will steer towards the contact , in which their infantry and other arms will oppose . Then , one or two will move forward and try to defeat the enemy force . The aim of an attack remains : moving against the positions occupied by the enemy , to dislodge it and then establish control of the target . Attacks are often feared by the infantry leads because of the high number of casualties suffered while advancing under enemy fire . The successful attacks based on a sufficient force , reconnaissance and bombing of preparation and maintenance of unit cohesion during its execution . Defense is the natural operation of counter - attack , in which the mission is to hold an objective and defeat enemy forces who seek to take . defensiveness offers numerous advantages to the infantry , including the ability in the use and site preparation , including the construction of fortifications to reduce exposure to enemy fire . An effective defense is based on the minimization of casualties caused by enemy fire , breaking the cohesion of enemy forces before the end of complete and prevention of penetration in the enemy defensive positions . Patrol is the most common infantry mission . Large - scale attacks and defensive efforts are very occasional , but patrols are constant . Patrols consist of small groups of infantry moving through areas where there is enemy activity in order to find its position and in order to ambush their own enemy patrols . Patrols are used not only in advanced areas , but also in the rear , where the enemy infiltrations are possible . Persecution is the function that often takes the Infantry . The objective of pursuit operations is the destruction of enemy forces that are no longer able to engage the friendly units before they can recover and rebuild their strength and become efficient again . The Infantry , traditionally in the past was the main force to destroy enemy units in this situation . In modern combat Infantry is used in pursuit of enemy forces in restricted terrain , especially in urban areas where faster forces , as armored , are unable to maneuver or avoid being ambushed . Escort is to protect other units from ambush , particularly from enemy infantry . This is one of the most important tasks of modern infantry , especially when operating with armored vehicles . In this capacity , the basic infantry conducts patrols in motion , hitting the ground you can hide enemy forces waiting to ambush armored friends and identifying enemy positions that could be damaged by heavier units . Maneuvering these operations consume most of the time an infantry unit . The infantry , like all combat units , many times maneuvering on the battlefield , under enemy attack . The Infantry has to maintain cohesion and readiness during the move to ensure their effectiveness at the time it reaches the target . Infantry traditionally relied on their own legs for mobility , but currently uses motorized and armored vehicles to carry . Reserve such missions involve the use of infantry in the rear , keeping patrol and security operations to prevent infiltration of the enemy . This is usually the best time for infantry units to integrate replacements to their units , and in order to service your equipment . In addition , soldiers can rest improving their readiness to come . However , the unit has to be ready for use at any time . Buildings can be carried out either in front or the rear and consist of the use of infantry troops as labor for the construction of field positions , roads , bridges , airfields and other infrastructure . Infantry is often given this task because of the number of staff in its stores . This mission can , however , decrease the unit ' s morale and limit their ability to maintain readiness and enable it to perform other missions . Defense key points happens when infantry units are tasked to protect certain points such as command posts and bases .