Dojo Darelir, the School of Xenograg the Sorcerer

The 6th-century [C.E. Byzantine] soldier was in fact much more than a cavalryman: he had become an all-around mounted warrior. With his bow he could skirmish at a distance, but he was also heavily armoured and well equipped for close mounted combat. When a steady force was needed to hold ground, he was quite happy to dismount and fight as a heavy infantryman. On many occasions Belisarius took only cavalrymen with him, and when Narses needed steady infantry, he dismounted his cavalry.

— Simon MacDowall, Late Roman Cavalryman: 236-565 AD, p. 24

…No one now alive has witnessed combat between organized forces using hand-to-hand weapons, for the last vestige of it disappeared one hundred fifty years ago when the bayonet charge became obsolete. We tend to think (assisted by the movies) that direct shock combat of the sort described above was much more common in premodern warfare than it was. In reality, it was always difficult to make foot soldiers seriously engage one another with edged weapons because of their natural tendency to keep out of one another’s way. We have already seen that the Persian and other Eastern armies put no faith in heavy infantry assault. The main function of their spearmen was to provide cover for their archers, and battles were won by cavalry and archers with a minimum of physical contact. Only the Greeks had developed a style of warfare that made shock combat inevitable, because their infantry formation was no loose huddle but a tight rectangle (phalanx) often eight ranks deep or more, its heavy shields a collective locking device, its sheer depth and weight propelling the men in the front ranks onto the spears of the enemy.

— Doyne Dawson, The Origins of Western Warfare, p. 48

The arquebusiers, belonging to the same unit as the pikemen, did not operate completely independently…. In the absence of obstructed terrain, the square of pikemen provided the only place of safety where the light infantry might take refuge from the enemy’s heavy cavalry. They could take a position on the flank of or behind the square, or, should the cavalry attack in flank or rear, many could find safety in the front ranks where the wall of pikes would protect them. In turn, the arquebusiers’ fire could support the pikemen’s defense, and the masses of the enemy’s heavy infantry or the horses and men of the attacking heavy cavalry would provide fine targets for arquebus balls. The Spaniards gradually increased the proportion of arquebusiers to pikemen until, by the end of the 16th century [C.E.], their regiments approached equal numbers of light and heavy infantry.

— Archer Jones, The Art of War in the Western World, p. 191

In the two great battles of the Peloponnesian War, at Delium and Mantinea, one sees the very beginning of the Greek infantry tactics of deep columns, reserves, integrated cavalry units, adaptation to terrain, and secondary maneuvers, which would only accelerate in the fourth century [B.C.E.] under Epaminondas and come to fruition with Philip and Alexander. Hoplite battle in the Peloponnesian War began a slow transformation, from phalanxes rather artificially deciding wars to hoplites becoming, part of an integrated force of horsemen, light-armed troops, and missile troops that could win theaters of conflict on the basis of military efficacy rather than traditional protocol.

— Victor Davis Hanson, A War Like No Other, p. 141

The army relied mainly upon archers and pikemen, some very lightly armored, some protected by a cuirass and a conical helmet, and carrying a short sword for close fighting. Coordinated with this infantry was the cavalry, which at first fought from chariots. Later on, when the warrior rode the horse (about 700 [B.C.E.]), he had the infantryman’s bow and spear. Still later came the most original Assyrian contribution to the art of warfare, siege artillery. No fortified city could withstand the assault of Assyrian engines. A choice body of troops fought beside the king, but it was the foot-bowmen who wrought havoc on the enemy.

The Assyrian army’s power cannot be entirely explained by the bravery of the individual soldier, the competence of the king-general, or the sheer numerical strength so easy to attain in a country where every able-bodied man was subject to military service. Perhaps it is better explained by the theory that the Assyrians used iron extensively. Indeed something like a revolution in the metal industry apparently took place under Sargon II (722-705 [B.C.E.]) when he invaded Urartu and exploited its iron mines. Cunning, too, aided Assyrian armies: an efficient espionage and intelligence service was conducted by the royal governors and bureaucrats in the provinces and centered in the king’s palace. Frequently when the troops entered a country they were aided by carefully organized fifth columns.

— Vincent Scramuzza, The Ancient World, p. 89-90

Emphasis mine.