Their appearance was said to be magnificance, they glittered with gold armlets and necklaces. vast quantities of which they wore about their persons The elaborate robes seen on the stone reliefs at Persepolis and glazed tiles of Susa are considered to be their parade dress, on campaign they wore the more practical Median dress. This included a richly embroided knee-length tunic, a tiara to cover the head, (a soft woollen or felt cap) and a corset with metal plates or scales worn under his tunic.

Command
The ten thousand Immortals were viewed as distinct from the rest of the army and organised as a separate division. Herodotus describes the organisation of Xerxes' force that he lead against Greece in 479 BC;

"The whole of the infantry was under the command of these (six) generals, (Mardonius, Tritantaechmes, Smerdomenes, Masistes, Gergis and Megabyzus) excepting the Ten Thousand. The Ten Thousand, who were all Persians and all picked men, were led by Hydarnes, the son of Hydarnes." ( Herodotus -The Histories, 7, 82)
When leaving Sardis with Xerxes, a space was left in the column of march to physically separate the Guard and Immortal regiments from the rest of the army. Even their provisions were carried separate from the rest of the army. The appearence of which was was very much different from that of the other contingents. The baggage train could include their concurbines which rode in litters and numerous servants, "handsomely dressed".

It was the Immortals who were given the honor of being the first to cross the Hellenespont into Europe, leading Xerxes invasion against Greece, their heads adawned with wreaths.

Armaments
The main weapons of the Immortals were the composite bow and iron-headed cornel wood spear. The spear was aproximately 7' in length with a counterweight on the butt-end rather than the iron spike that the Greeks used on their spears. One thousand Immortals carried spears with a golden pomegranate-shaped counterweight which must have been the file leaders or officers in charge of the ten men(Satapatish). The other nine thousand carried spears with a silver pomegranate shaped counter-weights.

Their composite bow was similar to the Median and Skythian style but the Persian style quiver may have been carried on the shoulder rather than on the hip as the Median type. A short sword (akinakes) or large dagger, completed the weaponry. Compared to the elite of the Greek forces, they were lightly armoured. They did not wear the bronze greaves or helmets or carry the heavy hoplon shield of the Greeks.

Although the Immortals are portrayed carrying bow and spear, it is thought that their battle formation was a mixed formation of archers, spearman and shield bearers, rather than a body a soldiers each armed identically. The equipment carried indicating the soldier's function and position in the battle line.

The Immortals seemed to have also used the "spara", or large wicker shield like the other Persian, Median or Cissian regiments. The "Spara" or gerrhon which is shown both in Greek art and at Persepolis where it is being held by a Persian guard. It was carried only by the front rank who used it to form a defensive barrier or shield wall.

An interesting photo in Charles Grants' article, 'Military Modelling', June 1976, shows a reenactment of Persian Immortals in 1971 marching in a military parade in Tehran, celebrating the 2500th anniversary of the founding of the Persian empire. It shows a regiments of Immortals, ten men across. The three front ranks are spearmen carrying the violin shield and short spear then two ranks of archers folowed by more spearmen.

It is Cyrus the Great who is credited for forming the division of 'Immortals'.
As the elite of the Persian army and commanded as a separate division to the rest of the army, it is thought that they only campaigned with the king himself. Campaigns and battles where they fought may include:

• Cyrus' campaign against Lydia , Babylon 547BC.
• Cambyses campaign against Egypt 525 BC.
• Darius' Indian campaign 520BC.
• Darius' Scythian campaign 513 BC.
• Xerxes campaign against Greece 479 BC.
  
  
  • Hellespont, under the command of Hydarnes, the Immortals were given the priveledge of being the first to cross the Hellespont bridge from Asia into Europe.
  • Thermoplyae, initially kept in reserve, Xerxes committed the Immortals against the Spartans only when all previous assaults were unsuccessful. They were also repulsed with heavy losses. Hydarnes then lead the Immortals on a night flanking march, overcoming the Phocian's guarding the pass and arriving at the Spartan rear in the morning.
  • After the naval defeat at Salimus, Xerxes made the decision to return to Sardis leaving Mardonius to complete the conquest of Greece. Mardonius was allowed to choose whichever troops he required. According to(Herodotus VIII, 113.) the Immortals were his first choice.
  • Plataea, despite Herodotus giving fairly detailed information about which troops were present at the battle of Plataea, there is no mention of the Immortals specifically. It is likely that they were among the 60,000 picked troops under the command of Artabazus that escorted Xerxes back to the Hellespont and continued to Sardis with Xerxes rather than return to Greece. Reasons why the Immortals may not have fought at Plataea.