Cavalry in the Persian army, and more precisely in the army of the Persian Empire, during the Achaemenid rule (around 550 BC - around 330 BC) always played a very important role and was treated as an elite formation in its own way. It was often recruited from noble Persian and Median families. In the course of battle, it was most often positioned on the wings of its own troops and was to perform a maneuver flanking the center of enemy troops. The Persian cavalry most often used relatively simple helmets, but not limiting the field of view. The basic weapons were usually javelins, short spears, short swords and daggers. Light shields and lamellar armor were rarely used as defensive weapons. The Persian cavalry, despite their good posture on the battlefield, failed to cope with the Macedonian cavalry during the expedition of Alexander the Great (334-323 BC).
Infantry in the Persian army, and more precisely in the army of the Persian state under the Achaemenid dynasty (from approx. 550 BC to approx. 330 BC), played an important role, performing various functions - from scouting to fighting in the open field in progress battles. Most often it was placed in the center of the Persian army's combat formation. Its exact number is only an estimate - the numbers given by the author of "The Acts" of Herodotus are rather perceived as unrealistic. It is assumed, however, that the number of Persian infantry during Xerxes' expedition to Greece (480-479 BC) could be from 100,000 to 200,000. people. However, these are still estimates. Undoubtedly, the elite of the Persian infantry was the Immortals unit, always composed of 10,000, recruited from the native Persians and Medes. This unit is certainly certified in sources during the reign of Cambyses (533-520 BC), and perhaps it was formed by his father - Cyrus the Great (559-530 BC). The soldiers of this formation were very well trained, had high morale and were armed with spears, bows and probably short swords. On the other hand, they had marginal protective equipment, which brought a deplorable effect during the battles at Marathon (490 BC) or Thermopylae (480 BC). It was not until the Greco-Persian wars that the soldiers of this formation probably received lamellar armor.