ROMAN LEGIONS & other ancients
THE SASSANID PERSIANS
In 226 AD the Sassanid Persians overthrew the Parthian monarchy. Chosroes I (5311-79 AD) quartered the empire (and the army) under four regional rulers. Befre that time there was one commander in chief of the entre army. Standard (but not exclusive) deployment for large armies was in five parts: a main battle line, a reinforcing line, a small reserve (the Immortals, elite cavalry), and two cavalry wings. Another tactic saw the cavalry forming a front line while the army advanced, only to retire to the wings and thus surprising with infantry an enemy who had expected to face mounted troops. Generals often oremained in the rear on non-combatant elephants. This was to provided a better view and to keep them from seeking personal glory in the front ranks.
Organization:
The Sassanian military showed an increasing degree of organization and profesionalism. Since the early days of the dynasty, all cavalry had been subject to official inspection and training. Khusro changed this procedure by his development of an "equipment list" to be obeyed at periodic musters. Even the royal troops were under its authority. The regulation set a requirement for body and horse armor, sword, lance, two bows, ax or mace, a shield, and paraphernalia.
Cavalry
Sassanian armies were usually less than one-third cavalry. Though, entire armies could sometimes be composed of only horsemen. The typical mounted soldier carried a bow in addition to the lance, and rode an armored horse, though only frontally armored with metal in the Byzantine style. The lighter-armored horsemen greatly outnumbered the heavily armored nobles. Increased availability of mail probably lead to better protection for more riders over time. Throughout this period, eastern cavalry would have made widespread use of leather and felt horse bards - important when facing nomad horse archers.
Typically, the wealthier the noble, the better his equipment. To improve the distribution of qulaity arms and armor, units were formed with support from the shahanshah (the king) . The most famous were the 10,000 Immortals. These elite troops were meant to emulate the ones form the time of Darius. They were a heavy assault force kept in reserve. Other such troops included: the pushtighban, who may have numbered 1000 and seem to have been a guard regiment at court. The gyanavspar, "sacrificers of their lives," were ecclesiastical cavalry or maybe mercenaries. The Royal Archers defended the throne. They may have numbered a hundred or more, and often served on foot. Periodically thousands of resettled captives, including Georgians, Alans, and others were incorporated into the army. They were resettled and eventually re-equipped to match they tactics of the Perisan forces.
Khusro I apparently redistributed some large estates and other income-producing properties to the lesser knights, or dihqans, thus creating a larger ammount of men eligible to fight as cavalry. Some Sassanian troops were paid in coins from the early 300s AD, these knights received land and a stipend in exchange for mounted service. They were divided by their class into five ranks, indicated by their dress.
Elephants seem usually to have been accompanied by large infantry contingents. They provided support from the rear of the foot formations. They were used along with the cavalry to frighten the enemy soldiers and horses. Because it was difficult to replace them, the elephants were typically held as a reserve force.
Infantry:
Before theAlexander the Greats occupation of Persia alot the army relied mostly on the infanty. When the Parthians came to power, the emphasis was put on mounted troops. The Sassanian Persians reorganizied again, designing an army with a core of two-thirds infantry. The native troops appear to be partly local militia, and partly levied peasants. There were contingents of archers, slingers, javelinmen., and heavy infantry. The paighan were a local militia and police force. They probably formed the bulk of the infantry seen in many Sassanian armies. Commanded by officers called tirbadh, they mostly served as archers behind large shields.
Battle began with the foot skirmishers exchanging missiles. The mail-armored footmen then advanced in ranks signalled by trumpet. All this was done in coordination of the cavalry.