Immortals (Greek: Ἀθάνατοι Athánatoi), or Persian Immortals, was the name given by the Greek historian Herodotus to a 10,000-strong unit of elite heavy infantry in the Achaemenid army. They served in a dual capacity, operating as an imperial guard and contributing to the ranks of the standing army. The force mainly consisted of Persians, along with Medes and Elamites. Essential questions regarding the unit's history and organization remain unanswered due to the lack of authoritative sources.^[2]

Herodotus describes the Immortals as heavy infantry led by the Persian military commander Hydarnes the Younger; they provided the professional corps of the Achaemenid army and numbered exactly 10,000 men. He stated that the unit's name stemmed from the fact that every dead, seriously wounded, or sick Immortal was immediately replaced with a new one, maintaining the corps as a cohesive entity with a constant strength.^[3]

Xenophon (Cyropaedia 6.4.1; 7.1.2) describes the guard of Cyrus the Great as having bronze breastplates and helmets, while their horses wore chamfrons and peitrels of bronze together with shoulder pieces that also protected the rider's thighs. Herodotus instead describes their armament as follows: wicker shields covered in leather, short spears, quivers, swords or large daggers, slings, and bows and arrows. They wore coats of scale armour. The spear counterbalances of the common soldiery were of silver; to differentiate commanding ranks, the officers' spear butt-spikes were of gold.^[3] The regiment was followed by a caravan of covered carriages, camels, and mules that transported their supplies, along with concubines and attendants to serve them; this supply train carried special food that was reserved only for their consumption.^[4][5]

The headdress worn by the Immortals is believed to have been a conical or rounded metal on top and scale or chains on the sides, resembling a ridge helmet or Phrygian cap; surviving Achaemenid coloured glazed bricks and carved reliefs represent the Immortals as wearing elaborate robes, hoop earrings, and gold jewellery, although these garments and accessories were most likely worn only for ceremonial occasions.^[6]

The Persian denomination of the unit is uncertain.^[7] This elite force is only referred to as the "Immortals" in sources based on Herodotus. There is evidence from Persian sources of the existence of a permanent corps, which provided a backbone for the tribal levies (raised by satraps) who, together with increasing numbers of mercenaries, made up the bulk of the Achaemenid army.^[8] However these do not record the name of "Immortals"; it is suggested that Herodotus' informant confused the word anûšiya- (lit. 'companion') with anauša- (lit. 'immortal'),^[3] but this theory has been criticized by German linguist Rüdiger Schmitt.^[2]

The Immortals played an important role in the Achaemenid conquest of Egypt under Cambyses II in 525 BCE, as well as in the Achaemenid conquest of Indus Valley (western Punjab and Sindh, now located in Pakistan) and European Scythia under Darius I in c. 518 BCE and 513 BCE, respectively. They also notably participated in the Battle of Thermopylae in 480 BCE during the Greco-Persian Wars and were amongst the Persian troops who occupied Greece in 479 BCE under Mardonius.^[3]

During the final decades of the Achaemenid Empire, the role expected of the Immortals' hazarapatish (lit. 'one thousand overseer') was extended to include that of chief minister to the King of Kings. The provision of a bodyguard, in direct attendance of the monarch, had already been allocated to a select thousand-strong detachment of the unit.

The Persian Immortals played an important role in Cyrus the Great’s conquest of Babylon, namely the Battle of Opis in 539 BCE. The well-established regiment were an elite corps of 10,000 heavy infantry in the Achaemenid military unit and were important to the Persian triumph over the Babylonian forces. Immortals’ “immortality” was renowned for maintaining its full strength through instant replacement whenever anyone of them fell out of the number by force of death or sickness in order to ensure a consistent and intimidating battle presence ^[9]. The strong battle presence made them a huge force and central element of Cyrus the Great’s strategy and tactics.

According to Herodotus, Persian strategy at Opis adapted a lot of surprise attack to exploit Babylonian vulnerabilities with Immortals discipline. Immortals’ versatility in both ranging engagements, as well as close-quarter combat with their short spears, bow and small sword allow Cyrus the Great maneuvered them into breaching Babylonian lines, which also been seen in later war like Thermopylae.^[10] Cook further supports this inference with nothing Immortal’s rigorous training and discipline, were what made them elite and perfect choice to lead charges and anchor key defensive position in the war.^[9]

Despite the lack of direct description toward Immortals in the field, their prominence as the Persian’s elite military unit implies a significant contribution. Scholars like Dandamaev and Vogelsang argue that their involvement in foundational victories like Battle of Opis reinforced their operational importance within the Achaemenid military framework.^[11]

The Battle of Opis was a transformative moment for Cyrus the Great and his Achaemenid Empire as it initiated the ascendancy over Mesopotamia and marked the first step for the conquest of Babylon later in history. The Immortals’ participation in the Battle of Opis victory solidified their reputation as the empire’s stalwart guardians, manifesting the elite military prowess and organizational replacement Achaemenid possessed. The fixed strength and population of 10,000 that sustained through a unique system of immediate replacement had fostered an image of invulnerability that amplified their psychological influences not only on both allies and foes, but also the Achaemenid empire image.^[12]

The legacy of Immortals from Battle of Opis is deeply intertwined with their establishment as the foundational pieces of Achaemenid armed forces. Their success in early fights like Battle of Opis, had underpinned their continued greatness under later rulers like Cambyses, Darius the Great and Xerxes, their presence could also be found at Thermopylae and Gaugamela engagement. Their continued success at different appearances catalyzed Achaemenid empire’s territory expansion, when they are not in combat, they acted as the Persian Palace Guard that had shaped the military traditions and reinforced their symbolic connection with Persian imperial authority.^[13]

The first recurrence of the word "Immortals" is in Roman historians' description of an elite cavalry unit in the army of the Sasanian Empire. Primary sources suggest that they numbered around 10,000 men in accordance with tradition, with the main formational difference being that they were heavy cavalry. However, recent scholarship has doubted the Roman description of the force, including their name, their size, and that they were modeled on the Achaemenid Immortals, although there may have been one or more of such distinct elite cavalry units during the Sasanian period. Their task was mainly to secure any breakthroughs and to enter battles at crucial stages.^[7]

The designation "Immortal" to describe a military unit was used twice during the era of the Byzantine Empire: first as elite heavy cavalry under John I Tzimiskes (r. 969–976) and then later under Nikephoritzes, the chief minister of Byzantine emperor Michael VII Doukas (r. 1071–1081), as the core of a new central field army following the disastrous Byzantine defeat at Manzikert to the Seljuk Turks in 1071.

During the 19th-century Napoleonic Wars, many French soldiers referred to Napoleon's Imperial Guard as "the Immortals".^[14]

Under Mohammad Reza Pahlavi, the last Shah of Iran, the Imperial Iranian Army included an all-volunteer known as the Javidan Guard (Persian: گارد جاویدان, romanized: Gârd-e Jâvidân, lit. 'Immortal Guard'), named after the ancient Persian royal guard. The Javidan Guard was based at the Lavizan Barracks in Tehran. By 1978, this elite force comprised a brigade of 4,000–5,000 men, including a battalion of Chieftain tanks. Following the 1979 Islamic revolution that ended the Imperial State of Iran and the Pahlavi dynasty, the "Immortal Guard" was disbanded.^[15]

The signature shield of the Achaemenid Empire's Immortals has been adopted in the insignia of the 65th Airborne Special Forces Brigade and the 55th Airborne Brigade of the Islamic Republic of Iran Army.

Greek authors were impressed by the immortals with their luxury – Herodotus noted that the immortals “showed of all the richest adornment by Persian” and “over and above this they made a brave show with the abundance of hold that they had” ^[16]. Quinte-Curce has also remarked that Immortals were “above all who were made imposing by an unheard-of luxury of opulence, they wore gold necklaces, gold-embroidered robes and the sleeved tunics which were also adorned with gems”.^[17]

Aelianus adds that the robes of the Immortals were “purple and yellow”, and Alexander the Great kept and used them in his service after he conquered the reign of the Achaemenids because of their impressive appearance. Immortals’ appearances were also found in the enameled brickwork of the Apadana in the palace of Darius I in Susa. Dressed in the regiment’s uniform that consisted of a felt diadem or bandana (a broad tunic), with embroidery, trousers and chain mail, though these were least likely to be worn in combat and only appeared in formal occasion.^[18]

As for the armament of the Immortals, they wore an embroidered tunic with sleeves that overlaid with a coat of scale armor that “looked like the scales of a fish” .^[16] The metal-made armor provided significant protection in the combat; Immortals protected their head by wearing a typical Persian troops headgear – tiara, a soft felt cap and covered up their feet with strapped shoes and boots. However, their primary defensive equipment consists of a large, wicker, leather shield. The tall and rectangular shield could be planted in the ground for cover and stop arrows. Based on need, the Immortals could also be equipped with a figure-8 boeotian shield for better mobility.^[16]

Offensively, the Immortals had several weapons at their disposal. While at range, they carried powerful bows with cane and reed arrows and normally stored in quivers to emphasize their archery capabilities and as a hallmark of Persian warfare.^[16] In close combat, the Immortals had a short spear with an iron, butt-spike tip, where higher rank commanders had gold while common soldiers had it in silver, to highlight the status differentiation. According to Herodotus, it is the most symbolic weapon for the Immortals. Finally, the Immortals would also have a small, short sword, the akinakes, as a backup secondary option.^[16]

The Immortals regiment was followed by a caravan of carts, dromedaries and mules that carry their women and slaves, as well as special foodstuffs.

Being an elite heavy infantry, the tactics of Persian Immortals involved heavy infantry formation where they used their bow, short spears, sword and wicker shields to cover them in offense and defense, while still striking the balance between mobility and protection. They adapted tight phalanx-like formations that is somewhat similar to Greek, but Immortals focused more on adaptability due to their military nature. Frontline Immortals will shielded up, and would get range support from the Immortals archers behind or could cooperate with other Persian military units to first penetrate the enemy’s frontline, then engaged into close combat with their swords and deadly spears.^[19]

Herodotus' account of two warrior elites—the hoplites of Sparta and the Immortals of Persia—facing each other in battle has inspired a set of fanciful depictions of the battle, especially with regard to the Immortals:

• In the 1962 film The 300 Spartans, the Immortals carry a spear and wicker shields like the actual Immortals. However, they are mostly dressed in black and other dark colors in contrast to historical depictions.^[15]
• Frank Miller's 1998 comic book 300 and the 2006 feature film adapted from it present a heavily fictionalized version of the Immortals at the Battle of Thermopylae in 480 BCE. These Immortals wear Mengu-style metal masks, appear to be inhuman or disfigured, and carry a pair of swords closely resembling Japanese wakizashis.^[15]
• The Immortals also appears in the film Meet the Spartans that is mainly a parody of the film 300.
• The History Channel's 2007 film Last Stand of the 300 also features the Immortals as part of the reconstruction of the historic battle at Thermopylae in ancient Greece. In this version, the Persian tiara that the Immortals habitually wore is depicted as a full-face black cloth mask transparent enough to see through.^[15]
• The second season of the show Deadliest Warrior featured the Persian Immortals in a simulated match-up against Celtic warriors. The Immortals were found to be victorious.
• In the video game Prince of Persia: The Lost Crown, the protagonist Sargon is part of an elite group called The Immortals, who in the game serve as soldiers in the Persian army as well as bodyguards to the royal family, including the titular prince.^{[citation needed]}

• History of Iran
• Military history of Iran

• Hicks, Jim (1975). The Persians. Time-Life Books. ISBN 9780809412983.
• Lendering, John (1997). ""Immortals"". Livius.
• Schmitt, Rüdiger (2004). "Immortals". Encyclopaedia Iranica.