Oxus chariot model.jpg|A golden chariot made during
Achaemenid Empire (550–330 BCE). Achaemenid true extent.png|The Achaemenid Empire at its greatest extent. Persepolis Apadana noerdliche Treppe Detail.jpg|Right: Persian soldier. Left: Median soldier. Persépolis. La Garde.jpg|Persian warriors. The Achaemenid Empire (559–330 BCE) was the first of the Persian Empires to rule over significant portions of Greater Iran. The empire possessed a "national army" of roughly 120.000–150.000 troops, plus several tens of thousands of troops from their allies. The Persian army was divided into regiments of a thousand each, called
hazarabam. Ten hazarabams formed a
haivarabam, or division. The best known haivarabam were the
Immortals, the King's personal guard division. The smallest unit was the ten-man
dathaba. Ten dathabas formed the hundred man
sataba. The royal army used a system of color
uniforms to identify different units. A large variety of colors were used, some of the most common being yellow, purple, and blue. However, this system was probably limited to native Persian troops and was not used for their numerous allies. The usual tactic employed by the Persians in the early period of the empire, was to form a
shield wall that archers could fire over. These troops (called
sparabara, or shield-bearers) were equipped with a large rectangular wicker shield called a spara, and armed with a short spear, measuring around six feet long. Though equipped and trained to conduct
shock action (hand-to-hand combat with spears, axes and swords), this was a secondary capability and the Persians preferred to maintain their distance from the enemy in order to defeat him with superior missile-power. The
bow was the preferred missile-weapon of the Persians. At maximum rate of fire a sparabara haivarabam of 10,000 men could launch approximately 100,000 arrows in a single minute and maintain this rate for a number of minutes. Typically the Persian
cavalry would open the battle by harassing the enemy with hit and run attacks – shooting arrows and throwing small javelins – while the Persian sparabara formed up their battle-array. Then the Persian cavalry would move aside and attempt to harass the flanks of the enemy. Defending against the Persian cavalry required the enemy infantry to congregate in dense static formations, which were ideal targets for the Persian archers. Even heavily armoured infantry like the Greek hoplites would suffer heavy casualties in such conditions. Enemy infantry formations that scattered to reduce casualties from the dense volleys of Persian arrows, were exposed to a close-in shock assault by the Persian cavalry. Torn by the dilemma between exposure to a gradual attrition by the arrows or to being overwhelmed by a cavalry charge on their flanks, most armies faced by the Persians succumbed. The major weaknesses of the typical Persian tactics were that proper application of these tactics required: a) A wide battlefield composed of fairly flat and expansive terrain that would not hinder the rapid movement of massed horses and where the cavalry could conduct proper flanking maneuvers. b) Good coordination between the cavalry, infantry, and missile units. c) An enemy inferior in mobility. d) An enemy lacking a combined-arms military. Most Persian failures can be attributed to one or more of these requirements not being met. Thus, the Scythians evaded the Persian army time and again because they were all mounted and conducted only hit-and-run raids on the Persians; at Marathon the Athenians deployed on a rocky mountainous slope and only descended to the plain after the Persian cavalry had reboarded their transport-ships – charging through the arrow-shower to conduct close-combat with spears and swords – a form of combat for which the Athenians were better equipped and better trained; at Thermopylae the Greek army deliberately deployed in a location that negated the Persians ability to use cavalry and missile-power, again forcing them to fight only head-on in close-combat and was forced to retreat only after the Persians were informed of a bypass that enabled them to circumvent this defensive position to defeat the Spartans; at Plataea the Persian attack was poorly coordinated and defeated piecemeal; Alexander the Great's Macedonian army that invaded the Persian empire was composed of a variety of infantry and cavalry types (combined-arms approach) that enabled it, together with Alexander's superior tactical generalship, to negate the Persian capabilities and, once again, force them to fight close-combat. == Seleucid Empire (312 BCE–63 BCE) ==