The chariot
Invented in the 3rd millennium bc, the first chariots seem to have been too slow and cumbersome to serve in combat, but about 2000 bc the light, horse-drawn, two-wheeled vehicles destined to revolutionize tactics appeared in the Western Steppe and Mesopotamia, Syria, and Turkey, from which they spread in all directions. In combination with the bow, the chariot represented a very effective system, so much so that in biblical times it became almost synonymous with military power. The great advantage of the chariot was its speed, which permitted it to drive circles around the phalanx, staying out of range while raining arrows on the foot soldiers. Once the latter had been thrown into disorder, it might be possible to put the chariots into formation, charge, and ride the enemy down. Relying on such tactics, the chariot-riding Aryan peoples were able to undertake some of the most extensive conquests in history, spreading over the Eurasian landmass and inflicting crushing defeats on the materially much more advanced Egyptian and Indian civilizations. The chariot’s principal drawbacks were its expense and unsuitability for difficult terrain. Also, it made inefficient use of manpower, since each vehicle required a crew of two and sometimes three men—only one of whom actually handled offensive weapons and struck at the enemy.
Light and heavy cavalry
The next development following chariots was cavalry, which took two forms. From Mongolia to Persia and Anatolia—and, later, on the North American plains as well—nomadic peoples fought principally with missile weapons, especially the bow in its short, composite variety. Equipped with only light armour, these horsemen were unable to hold terrain or to stand on the defensive. Hence, they were forced to employ their characteristic highly mobile “swarming” tactics, riding circles around the enemy, keeping their distance from him, showering him with arrows, engaging in feigned retreats, luring him into traps and ambushes, and forming into a solid mass only at the end of the battle with the aim of delivering the coup de grace. Being obliged to keep their possessions few and light, nomads typically were unable to compete with sedentary civilizations in general material development, including not least metallurgy. Nevertheless, as the Mongols’ campaigns were to show, their war-making methods, natural hardihood, and excellent horsemanship made them the equal of anyone in either Asia or Europe until at least the end of the 13th century ad.
Among the technically more advanced sedentary civilizations on both edges of the Eurasian landmass, a different kind of cavalry seems to have emerged shortly after 1000 bc. Reliefs from great Assyrian palaces show horsemen, clad in armour and armed with spear or lance, who were used in combination with other troops such as light and heavy infantry. The function of these cataphracts (from the Greek word for “armour”) was not to engage in long-distance combat but to launch massed shock action, first against the enemy cataphracts and then, having gained the field, against the enemy foot. The fact that ancient cavalry apparently did not possess the stirrup has often led modern historians to question the mounted soldier’s effectiveness. They argue that, since riders held on only by pressure of their knees, their ability to deliver shock was limited by the fear of falling off their mounts. This argument fails to note that, particularly in Hellenistic times and again in late Roman ones, cavalry forces did indeed play an important, often decisive, part in countless battles. Still, it is true that never during classical antiquity did cavalry succeed in replacing the formations of heavy infantry that remained the backbone of every army.
Combined infantry and cavalry
Classical Greek warfare, as mentioned above, consisted almost exclusively of frontal encounters between massive phalanxes on both sides. However, about the time of the Peloponnesian War (431–404 bc), the phalanx became somewhat more articulated. This permitted the introduction of elementary tactical maneuvers such as massing one’s forces at a selected point, outflanking the enemy, and the oblique approach (in which one wing stormed the enemy while the other was held back). In addition, the phalanx began to be combined with other kinds of troops, such as light infantry (javelin men and slingers) and cavalry. Indeed, the history of Greek warfare can be understood as a process by which various previously existing types of troops came to be combined, integrated, and made to support one another. This development gained momentum in 4th-century battles, such as the one fought by Thebes against the Thessalians at Cynoscephalae in 364 bc, and it culminated in the hands of Alexander III the Great, whose army saw most of these different troops fighting side by side. The major exception was horse archers, which were incompatible with a settled way of life and which never caught on in the West. Another was the chariot, which was already obsolescent and, except in backward Britain, disappeared almost completely after its defeat at the Battle of Gaugamela in 331 bc.
Commanding standing armies consisting of professionals, Alexander and his successors (diodochoi) operated on a much greater scale than did most of their predecessors. The most important diodochoi were quite capable of concentrating 80,000 to 100,000 men at a single spot, as did both Ptolemy IV and his Seleucid opponent Antiochus III at Raphia in 217 bc. These armies typically went into battle with a force of light infantrymen in front (elephants were sometimes used, but on the whole they proved as dangerous to their own side as to the enemy). Behind the light troops came the heavy phalanx, flanked by cavalry on both sides. The action would start with each side’s light troops trying to drive the opponents back upon their phalanx, thus throwing it into disorder. Meanwhile, the cavalry stood on both sides. Usually one wing, commanded either by the king in person or by one of his closest subordinates, would storm forward. If it succeeded in driving away the opposing cavalry—and provided it remained under control—it could then swing inward and act as the hammer to the phalanx’s anvil. Such were the methods by which the great Hellenistic battles such as Gabiene (317 bc) and Ipsus (301 bc) were won. The same applied to the one fought by Hannibal at Cannae in 216 bc; this owed its exceptionally decisive character to the envelopment of the Roman infantry by two cavalry arms instead of one.

The legion
Though its exact origins are unknown, the Roman legion seems to have developed from the phalanx. In fact, it was a collection of small, well-integrated, well-coordinated phalanxes arrayed in checkerboard formation and operating as a team. Hellenistic heavy infantry relied on the pike almost exclusively; the legion, by contrast, possessed both shock and firepower—the former in the form of the short sword, or gladius, the latter delivered by the javelin, or pilum, of which most (after 100 bc, all) legionnaires carried two. Screening was provided by light troops moving in front, cohesion by pikemen in the third and rearmost rank. Short arms made it easier for individual soldiers or subunits to turn and change direction. Too, careful articulation, a well-rehearsed command system, and the use of standards—which do not seem to have been carried by Hellenistic armies—made the legion a much more flexible organization than the phalanx. No Greek army could have imitated the movement carried out by Caesar’s troops at Ruspinum in Africa in 47 bc, when part of a legion was made to turn around and face an enemy cavalry force coming from the rear. As numerous battles showed, where the terrain was uneven and the chain of command broke down, the legion’s advantage was even more pronounced. A phalanx whose ranks were thrown into disorder and penetrated by the enemy’s infantrymen was usually lost; a legionary commander could rely on his soldiers’ swords to deal with intruders, meanwhile bringing up additional units from both flanks.
As a formation whose main power consisted of its heavy infantry, the legion remained unmatched until the introduction of firearms and beyond. Attempts to imitate its armament and methods were made right down to the 16th century, and even today some countries still call their forces legions in commemoration of its prowess. During the 1st century bc, legionary organization underwent some changes at the hands of Gaius Marius and Lucius Cornelius Sulla until it reached the zenith of its development about the time of Caesar. Subunits became larger, and the legion incorporated a detachment of heavy cavalry as well as field artillery in the form of catapults—thus turning into a combined-arms unit and becoming a true forerunner of the modern division. Yet the legion, too, had its limitations when it came to fighting in the dense forests of Germany or, even more so, the open deserts of the Middle East. As Marcus Licinius Crassus’ disastrous defeat at Carrhae in 53 bc demonstrated, it met its match in the eastern light cavalry, with which it could never really come to grips, so that, even after repeated attempts, the Romans failed to subdue Parthia as they had so many other countries. The lesson was not lost. From the time of Belisarius in the 6th century ad, the Byzantine army always supplemented its infantry and heavy cavalry with units of horse archers, usually consisting of mercenaries recruited from various barbarian tribes. In this way, they were able to counter the Arabs and, later, the Seljuqs.