Infantry in the context of "United States Marine Corps"

The Macedonian phalanx (Greek: Μακεδονική φάλαγξ) was an infantry formation developed by Philip II from the classical Greek phalanx, of which the main innovation was the use of the sarissa, a 6-metre pike. It was famously commanded by him during the rise of Macedon and by his son Alexander the Great during his conquest of the Achaemenid Empire and his other campaigns between 336 and 325 BC.

The Macedonian phalanx model then spread throughout the Hellenistic world, where it became the standard battle formation for pitched battles. During the Second Macedonian War (200–197 BC), Roman-Seleucid War (191–188 BC) and Third Macedonian War (171–168 BC) against the Roman Republic, the Hellenistic phalanx, both the Antigonid phalanx and the Seleucid phalanx, appeared less adaptable to changing conditions on the battlefield against the more flexible Roman legions.

Combined arms is an approach to warfare that seeks to integrate different combat arms of a military to achieve mutually complementary effects—for example, using infantry and armour in an urban environment in which each supports the other.

According to the strategist William S. Lind, combined arms can be distinguished from the concept of "supporting arms" as follows:

The military nature of Mycenaean Greece (c. 1800–1050 BC) in the Late Bronze Age is evident by the numerous weapons unearthed, warrior and combat representations in contemporary art, as well as by the preserved Greek Linear B records. The Mycenaeans invested in the development of military infrastructure with military production and logistics being supervised directly from the palatial centres.

Late Bronze Age Greece was divided into a series of warrior kingdoms, the most important being centered in Mycenae, to which the culture of this era owes its name, Tiryns, Pylos and Thebes. From the 15th century BC, Mycenaean power started expanding towards the Aegean, the Anatolian coast and Cyprus. Mycenaean armies shared several common features with other contemporary Late Bronze Age powers: they were initially based on heavy infantry, with spears, large shields and in some occasions armor. In the 13th century BC, Mycenaean units underwent a transformation in tactics and weaponry and became more uniform and flexible and their weapons became smaller and lighter. Some representative types of Mycenaean armor/weapons were the boar's tusk helmet and the "Figure-of-eight" shield. Moreover, most features of the later hoplite panoply of Classical Greece were already known at this time.

The Battle of the Kerch Peninsula, which commenced with the Soviet Kerch-Feodosia Landing Operation (Russian: Керченско-Феодосийская десантная операция, romanized: Kerchensko-Feodosiyskaya desantnaya operatsiya) and ended with the German Operation Bustard Hunt (German: Unternehmen Trappenjagd), was a World War II battle between Erich von Manstein's German and Romanian 11th Army and the Soviet Crimean Front forces in the Kerch Peninsula, in the eastern part of the Crimean Peninsula. It began on 26 December 1941, with an amphibious landing operation by two Soviet armies intended to break the Siege of Sevastopol. Axis forces first contained the Soviet beachhead throughout the winter and interdicted its naval supply lines through aerial bombing. From January through April, the Crimean Front launched repeated offensives against the 11th Army, all of which failed with heavy losses. The Red Army lost 352,000 men in the attacks, while the Axis suffered 24,120 casualties. Superior German artillery firepower was largely responsible for the Soviet debacle.

On 8 May 1942, the Axis attacked in a major counteroffensive codenamed Trappenjagd which concluded by around 19 May 1942 with the defeat of the Soviet defending forces. Manstein used a large concentration of airpower, heavily armed infantry divisions, concentrated artillery bombardments and amphibious assaults to break through the Soviet front in its southern portion in 210 minutes, swing north with the 22nd Panzer Division to encircle the Soviet 51st Army on 10 May and annihilate it on 11 May. The remnants of the 44th and 47th armies were pursued to Kerch, where the last pockets of organized Soviet resistance were defeated by 19 May. The decisive element in the German victory was the campaign of airstrikes against the Crimean Front by Wolfram von Richthofen's 800 aircraft VIII. Fliegerkorps, which flew an average of 1,500 sorties per day in support of Trappenjagd and constantly attacked Soviet field positions, armored units, troop columns, medical evacuation ships, airfields, and supply lines. German bombers used up to 6,000 canisters of SD-2 anti-personnel cluster munitions to kill masses of fleeing Soviet infantrymen.

A pike is a long thrusting spear formerly used in European warfare from the Late Middle Ages and most of the early modern period, and wielded by foot soldiers deployed in pike square formation, until it was largely replaced by bayonet-equipped muskets. The pike was particularly well known as the primary weapon of Spanish tercios, Swiss mercenaries, German Landsknecht units and French sans-culottes. A similar weapon, the sarissa, had been used in antiquity by Alexander the Great's Macedonian phalanx infantry.

Combat arms (or fighting arms in non-American parlance) are troops within national armed forces who participate in direct tactical ground combat. In general, they are units that carry or employ weapons, such as infantry, cavalry, and artillery units. The use of multiple combat arms in mutually supporting ways is known as combined arms. In some armies, notably the British Army and Canadian Army, artillery and combat engineer units are categorized as combat support, while in others, such as the U.S. Army, they are considered part of the combat arms. Armored troops constitute a combat arm in name, although many have histories derived from cavalry units.

Artillery is included as a combat arm primarily based on the history of employing cannons in close combat, and later in the anti-tank role until the advent of anti-tank guided missiles. The inclusion of special forces in some armed forces as a separate combat arm is often doctrinal because the troops of special forces units are essentially specialized infantry, often with historical links to ordinary light infantry units.

Artillery consists of ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during sieges, and led to heavy, fairly immobile siege engines. As technology improved, lighter, more mobile field artillery cannons were developed for battlefield use. This development continues today; modern self-propelled artillery vehicles are highly mobile weapons of great versatility generally providing the largest share of an army's total firepower.

Originally, the word "artillery" referred to any group of soldiers primarily armed with some form of manufactured weapon or armour. Since the introduction of gunpowder and cannon, "artillery" has largely meant cannon, and in contemporary usage, usually refers to shell-firing guns, howitzers, and mortars (collectively called barrel artillery, cannon artillery or gun artillery) and rocket artillery. In common speech, the word "artillery" is often used to refer to individual devices, along with their accessories and fittings, although these assemblages are more properly called "equipment". However, there is no generally recognized generic term for a gun, howitzer, mortar, and so forth: the United States uses "artillery piece", but most English-speaking armies use "gun" and "mortar". The projectiles fired are typically either "shot" (if solid) or "shell" (if not solid). Historically, variants of solid shot including canister, chain shot and grapeshot were also used. "Shell" is a widely used generic term for a projectile, which is a component of munitions.

Historically, cavalry (from the French word cavalerie, itself derived from cheval meaning "horse") are groups of soldiers or warriors who fight mounted on horseback. Until the 20th century, cavalry were the most mobile of the combat arms, operating as light cavalry in the roles of reconnaissance, screening, and skirmishing, or as heavy cavalry for decisive economy of force and shock attacks. An individual soldier in the cavalry is known by a number of designations depending on era and tactics, such as a cavalryman, horseman, trooper, cataphract, knight, drabant, hussar, uhlan, mamluk, cuirassier, lancer, dragoon, samurai or horse archer. The designation of cavalry was not usually given to any military forces that used other animals or platforms for mounts, such as chariots, camels or elephants. Infantry who moved on horseback, but dismounted to fight on foot, were known in the early 17th to the early 18th century as dragoons, a class of mounted infantry which in most armies later evolved into standard cavalry while retaining their historic designation.

Cavalry had the advantage of improved mobility, and a soldier fighting from horseback also had the advantages of greater height, speed, and inertial mass over an opponent on foot. Another element of horse mounted warfare is the psychological impact a mounted soldier can inflict on an opponent.