Infantry tactics are the combination of military concepts and methods used by infantry to achieve tactical objectives during combat. The role of the infantry on the battlefield is, typically, to close with and engage the enemy, and hold territorial objectives; infantry tactics are the means by which this is achieved. Infantry commonly makes up the largest proportion of an army's fighting strength, and consequently often suffers the heaviest casualties. Throughout history, infantrymen have sought to minimise their losses in both attack and defence through effective tactics. (For a wider view of battle and theater tactics see: Military strategy)
Infantry tactics are the oldest method of warfare and span all eras. In different periods, the prevailing technology of the day has had an important impact on infantry tactics. In the opposite direction, tactical methods can encourage the development of particular technologies. Similarly, as weapons and tactics evolve, so do the tactical formations employed, such as the Greek phalanx, the Spanish tercio, the Napoleonic column, or the British 'thin red line'. In different periods the numbers of troops deployed as a single unit can also vary widely, from thousands to a few dozen.
Modern infantry tactics vary with the type of infantry deployed. Armoured and mechanised infantry are moved and supported in action by vehicles, while others may operate amphibiously from ships, or as airborne troops inserted by helicopter, parachute or glider, whereas light infantry may operate mainly on foot. In recent years, peacekeeping operations in support of humanitarian relief efforts have become particularly important. Tactics also vary with terrain. Tactics in urban areas, jungles, mountains, deserts or arctic areas are all markedly different.
Ancient history
The infantry phalanx was a Sumerian tactical formation as far back as the third millennium BC. It was a tightly knit group of hoplites, generally upper and middle-class men, typically eight to twelve ranks deep, armored in helmet, breastplate, and greaves, armed with two-to-three metre (6~9 foot) pikes and overlapping round shields. It was most effective in narrow areas, such as Thermopylae, or in large numbers. Although the early Greeks focused on the chariot, because of local geography, the phalanx was well developed in Greece and had superseded most cavalry tactics by the Greco-Persian Wars. In the fourth century BC Philip II of Macedon reorganized his army, with emphasis on phalanges, and the first scientific military research. Theban and Macedonian tactics were variations focused on a concentrated point to break through the enemy phalanx, following the shock of cavalry. Carefully organized—into tetrarchia of 64 men, taxiarchiae of two tetrarchiae, syntagmatae of two taxiarchiae, chilliarchiae of four syntagmatae, and phalanges of four chilliarchiae, with two chilliarchiae of peltasts and one chilliarchia each of psiloi and epihipparchy (cavalry) attached The simple phalanx could be combined into a grand phalanx of four simple phalanges, a formation equivalent to a modern army corps.—and thoroughly trained, these proved exceedingly effective in the hands of Alexander III of Macedon.
However, as effective as the Greek phalanx was, it was inflexible. Rome made their army into a complex professional organization, with a developed leadership structure and a rank system. The Romans made it possible for small-unit commanders to receive rewards and medals for valor and advancement in battle. Another major advantage was a new tactical formation, the manipular legion (adopted around 300BC), which could operate independently to take advantage of gaps in an enemy line, as at the Battle of Pydna. Perhaps the most important innovation was improving the quality of training to a level not seen before. Although individual methods were used by earlier generations, the Romans were able to combine them into an overwhelmingly successful army, able to defeat any enemy for more than two centuries.
The Roman tactical system
On the infantry level, the Roman Army adapted new weapons: the pilum (a piercing javelin), the gladius (a short thrusting sword), and the scutum (a large convex shield) providing protection against most attacks without the inflexibility of the phalanx. Generally, battle would open with a volley of light pila from up to (and frequently far less), followed by a volley of heavy pila just before the clashing with scuta and gladii. Roman soldiers were trained to stab with these swords instead of slash, always keeping their shields in front of them, maintaining a tight shield-wall formation with their fellow soldiers. To motivate the Roman soldier to come within two metres (6 ft) of his enemy (as he was required to do with the gladius) he would be made a citizen after doing so, upon completion of his term of service. Roman infantry discipline was strict and training constant and repetitive.
The manipular legion was an improvement over the phalanx on which it was based, providing flexibility and responsiveness unequalled before that time. By increasing dispersal, triple that of a typical phalanx, the manipular legion had the unanticipated benefit of reducing the lethality of opposing weapons.. Covering a wider area naturally reduces the tendency of any one soldier to be killed. Coupled with superb training and effective leaders, the Roman army was the finest in the world for centuries. The army's power on the field was such that its leaders avoided most fortifications, preferring to meet the enemy on open ground. To take an enemy-held fortification, the Roman army would cut off any supply lines, build watchtowers around the perimeter, set up catapults, and force the enemy to attempt to stop them from reducing the fortification's walls to rubble. The Roman army's achievements were carefully carved in stone on Trajan's Column, and are well documented by artifacts strewn about battlefields all over Europe.
Middle Ages After the fall of the Roman Empire, many of the ingenious tactics they used disappeared. Tribes such as the Visigoths and Vandals preferred to simply rush their enemies in a massive horde. These tribes would often win battles against more advanced enemies by achieving surprise and outnumbering their foes. Born out of the partition of the Roman Empire, the Byzantine Empire created an effective military. Its conscripts were well-paid and led by commanders educated in military tactics and history. However, the army mostly relied on cavalry, making the infantry a smaller portion of its overall force.
The Vikings were able to be effective against stronger enemies through surprise and mobility. Like guerrillas in other wars, the Vikings could decide when and where to attack. In part because of their flat bottomed ships, which enabled them to sneak deep into Europe by river before carrying out an attack, the Vikings could frequently catch their enemies by surprise. Monasteries were common targets because they were seldom heavily defended and often contained substantial amounts of valuables.
Battles of the Middle Ages were often smaller than those involving the Roman and Grecian armies of Antiquity. Armies (much like the states of the period) were more decentralized. There was little systematic organisation of supplies and equipment. Leaders were often incompetent; their positions of authority often based on birth, not ability. Most soldiers were much more loyal to their feudal lord than their state, and insubordination within armies was common. However, the biggest difference between previous wars and those of the Middle Ages was the use of heavy cavalry, particularly knights. Knights could often easily overrun infantry armed with swords, axes, and clubs. Infantry typically outnumbered knights somewhere between five and ten to one. They supported the knights and defended any loot the formation had. Infantry armed with spears could counter the threat posed by enemy cavalry. At other times pits, caltraps, wagons or sharpened wooden stakes would be used as protection from charging cavalry, while archers brought down the enemy horsemen with arrows; the English used stakes to defend against French knights at the Battle of Agincourt in 1415.
Pikemen often became a substitute for communities and villages who could not afford large forces of heavy cavalry. The pike could be up to long, whereas the spear was only 6 to in length. Archers would be integrated into these forces of spearmen or pikemen to rain down arrows upon an enemy while the spears or pikes held the enemy at bay. Polearms were improved again with the development of the halberd. The halberd could be the length of a spear, but with an axe head which enabled the user to stab or chop the enemy cavalry with either the front of the axe or a thin point on the opposite side. The Japanese also created polearms. The naginata consisted of an approximately long shaft and a blade. The naginata was often used by women to guard a castle in the absence of men.
The crossbow, which did not require trained archers, was frequently used in armies where the extensive training necessary for longbow was not practical. The biggest disadvantage of crossbows was the slow reloading time. With the advent of steel and mechanical drawing aids, crossbows became more powerful than ever. Armor proof against longbows and older crossbows could not stop quarrels from these improved weapons. Pope Innocent II put a ban on them, but the move toward using this lethal weapon had already started.
The first gunpowder weapons usually consisted of metal tubes tied down to wooden staves. Usually, these weapons could only be fired once. These gonnes, or hand cannons, were not very accurate, and would usually be fired from city walls or in ambush. Like the crossbow, the gonne did not require trained soldiers and could penetrate the armor worn by enemy soldiers. Ranged weapon users were protected by soldiers with melee weapons. Knights would be on either sides of this force and close in on the enemy to destroy them after they had been weakened by volleys. The introduction of firearms presaged a social revolution; even an illiterate peasant could kill a noble knight.
Modern history
Early modern period
As firearms became cheaper and more effective, they grew to widespread use among infantry beginning in the 16th century. Requiring little training, firearms soon began to make swords, maces, bows, and other weapons obsolete. Pikes, as a part of pike and shot formation, survived a good deal longer. By the mid-16th century, firearms had become the main weapons in many armies. The main firearm of that period was the arquebus. Although less accurate than the bow, an arquebus could penetrate most armours of the period and required little training. In response, armor thickened, making it very heavy and expensive. As a result, the cuirass replaced the mail hauberk and full suits of armour, and only the most valuable cavalry wore more than a padded shirt.
Soldiers armed with arquebuses were usually placed in three lines so one line would be able to fire, while the other two could reload. This tactic enabled an almost constant flow of gunfire to be maintained and made up for the inaccuracy of the weapon. In order to hold back cavalry, wooden palisades or pikemen would be in front of arquebusiers. An example of this is the Battle of Nagashino.