The Phrygian cap (), also known as Thracian capTsiafaki, Despoina. "Ancient Thrace and the Thracians through Athenian eyes." Thracia 21 (2016): 261–282.Herodotus , 6.45 and 7.73, "Thus fared the fleet; and meanwhile Mardonios and the land-army while encamping in Macedonia were attacked in the night by the Brygian Thracians, and many of them were slain by the Brygians and Mardonios himself was wounded."; "Now the Phrygians, as the Macedonians say, used to be called Brigians during the time that they were natives of Europe and dwelt with the Macedonians; but after they had changed into Asia, with their country they changed also their name and were called Phrygians. The Armenians were armed just like the Phrygians, being settlers from the Phrygians."Strabo , 7.3.2, "Now the Greeks used to suppose that the Getae were Thracians; and the Getae lived on either side the Ister, as did also the Mysi, these also being Thracians and identical with the people who are now called Moesi; from these Mysi sprang also the Mysi who now live between the Lydians and the Phrygians and Trojans. And the Phrygians themselves are Brigians, a Thracian tribe, as are also the Mygdonians, the Bebricians, the Medobithynians, the Bithynians, and the Thynians, and, I think, also the Mariandynians. These peoples, to be sure, have all utterly quitted Europe, but the Mysi have remained there. And Poseidonius seems to me to be correct in his conjecture that Homer designates the Mysi in Europe (I mean those in Thrace) when he says, "But back he turned his shining eyes, and looked far away towards the land of the horse-tending Thracians, and of the Mysi, hand-to‑hand fighters" for surely, if one should take Homer to mean the Mysi in Asia, the statement would not hang together." and liberty cap, is a soft conical cap with the apex bent over, associated in antiquity with several peoples in Eastern Europe, Anatolia, and Asia. The Phrygian cap was worn by Thracians, Dacians, Persians, Medes, Scythians, Trojans and Phrygians after whom it is named. The oldest known depiction of the Phrygian cap is from Persepolis in Iran.

Although Phrygian caps did not originally function as liberty caps, they came to signify freedom and the pursuit of liberty first in the American Revolution and then in the French Revolution,Richard Wrigley, "Transformations of a revolutionary emblem: The Liberty Cap in the French Revolution, French History 11(2) 1997, p. 132. particularly as a symbol of Jacobinism (in which context it has been also called a Jacobin cap). The original cap of liberty was the Roman pileus, the felt cap of emancipated slaves of ancient Rome, which was an attribute of Libertas, the Roman goddess of liberty. In the 16th century, the Roman iconography of liberty was revived in emblem books and numismatic handbooks where the figure of Libertas is usually depicted with a pileus.Carol Louise Janson, "The Birth of Dutch Liberty. Origins of the Pictorial Imagery", Diss. phil. University of Minnesota 1982 (microfilm), p. 35. The most extensive use of this headgear as a modern symbol of freedom in the first two centuries after the revival of Roman iconography occurred in the Netherlands, where it became a popular headdress.ibd. p. 98. In the 18th century, the traditional liberty cap was widely used in English prints, and from 1789 also in French prints; by the early 1790s, it was regularly used in the Phrygian form.

It was adopted in place of a crown on the coats of arms of the Argentina, Cuba, and Nicaragua republics as a symbol of their struggle for liberation and independence. It thus came to be identified as a symbol of republican government. A number of national personifications, including France's Marianne and the United States' Columbia are commonly depicted wearing the Phrygian cap.

In antiquity In the Iranian world

What came to be labelled as the Phrygian cap was originally used by several Iranian peoples, including the Scythians, the Medes, and the Persians. From the reports of the ancient Greeks, it appears that the Iranian variant also was a soft headdress and called a tiara.

The Greeks identified one variant with their eastern neighbors and labeled it the "Phrygian cap", although it was actually worn by nearly all Iranian tribes, from the Cappadocians (Old Persian Katpatuka) in the west to the Sakas (OPers. Sakā) in the northeast. This and other variants can be observed in the reliefs at Persepolis. All seem to have been made of soft material with long flaps over the ears and the neck, but the form of the top varies. The famous "upright (orthē) tiara" was worn by the king. Members of the Median upper class wore high, crested tiaras.

In the early Hellenistic world

By the 4th century BC (early Hellenistic period), the Phrygian cap was associated with Phrygian Attis, the consort of Cybele, the cult of which had by then become Hellenized. The cap appears in depictions of the mythological kings Midas and Rhesus of Thrace, the legendary bard Orpheus and other Thraco-Phrygians portrayed in Greek vase-paintings and sculpture.Lynn E. Roller, "The Legend of Midas", Classical Antiquity, 2.2 (October 1983:299–313) p. 305. Such images predate the earliest surviving literary references to the cap.

By extension, the Phrygian cap also came to be applied to several other non-Greek-speaking peoples ("barbarians" in the classical sense). Most notable of these extended senses of "Phrygian" were the Trojans and other western Anatolian peoples, who in Greek perception were synonymous with the Phrygians, and whose heroes Paris, Aeneas, and Ganymede were all regularly depicted with a Phrygian cap. Other Greek earthenware of antiquity also depict Amazons and so-called "Scythian" archers with Phrygian caps. Although these are military depictions, the headgear is distinguished from "Phrygian helmets" by long ear flaps, and the figures are also identified as "barbarians" by their trousers. The headgear also appears in 2nd-century BC Boeotian Tanagra figurines of an effeminate Eros, and in various 1st-century BC statuary of the Commagene, in eastern Anatolia. Greek representations of Thracians also regularly appear with Phrygian caps, most notably Bendis, the Thracian goddess of the Moon and the hunt, and Orpheus, a legendary Thracian poet and musician.

While the Phrygian cap was of wool or soft leather, in pre-Hellenistic times the Greeks had already developed a military helmet that had a similarly characteristic flipped-over tip. These so-called "Phrygian helmets" (named in modern times after the cap) were usually of bronze and in prominent use in Thrace, Dacia, Magna Graecia, and the rest of the Hellenistic world from the 5th century BC up to Roman times. Owing to their superficial similarity, the cap and helmet are often difficult to distinguish in Greek art (especially in black-figure or red-figure earthenware) unless the headgear is identified as a soft flexible cap by long earflaps or a long neck flap. Also confusingly similar are the depictions of the helmets used by cavalry and light infantry (cf. Peltasts of Thrace and Paeonia), whose headgear – aside from the traditional alopekis caps of fox skin – also included stiff leather helmets in imitation of the bronze ones.

In the Roman world

The Greek concept passed to the Romans in its extended sense, and thus encompassed not only to Phrygians or Trojans (which the Romans also generally associated with the term "Phrygian"), but also the other near-neighbours of the Greeks. On Trajan's Column, which commemorated Trajan's epic wars with the Dacians (101–102 and 105–106 AD), the Phrygian cap adorns the heads of Dacian warriors. The prisoner, accompanying Trajan in the monumental, three-meter-tall statue of Trajan in the ancient city of Laodicea, is wearing a Phrygian cap. Parthians appear with Phrygian caps in the 2nd-century Arch of Septimius Severus, which commemorates Roman victories over the Parthian Empire. Likewise with Phrygians caps, but for Gauls, appear in 2nd-century friezes built into the 4th-century Arch of Constantine.

The Phrygian cap reappears in figures related to the first- to fourth-century religion of Mithraism. This astrology-centric Roman mystery cult (cultus) projected itself with pseudo-Oriental trappings (known as perserie in scholarship) in order to distinguish itself from both traditional Roman religion and from the other mystery cults. In the artwork of the cult (e.g. in the so-called "tauroctony" cult images), the figures of the god Mithras as well as those of his helpers Cautes and Cautopates are routinely depicted with a Phrygian cap. The function of the Phrygian cap in the cult are unknown, but it is conventionally identified as an accessory of its perserie.

Early Christian art (and continuing well into the Middle Ages) build on the same Greco-Roman perceptions of (Pseudo-)Zoroaster and his "Magi" as experts in the arts of astrology and magic, and routinely depict the "three wise men" (that follow a star) with Phrygian caps.

As a symbol of liberty

From Phrygian to liberty cap In late Republican Rome, a soft felt cap called the pileus served as a symbol of freemen (i.e. non-slaves) and was symbolically given to slaves upon manumission, thereby granting them not only their personal liberty, but also libertas – freedom as citizens, with the right to vote (if male). Following the assassination of Julius Caesar in 44 BCE, Brutus and his co-conspirators instrumentalized this symbolism of the pileus to signify the end of Caesar's dictatorship and a return to the (Roman) republican system.Cf. Appian, Civil Wars 2:119: "The murderers wished to make a speech in the Senate, but as nobody remained there they wrapped their togas around their left arms to serve as shields, and, with swords still reeking with blood, ran, crying out that they had slain a king and tyrant. One of them bore a cap on the end of a spear as a symbol of freedom, and exhorted the people to restore the government of their fathers and recall the memory of the elder Brutus and of those who took the oath together against ancient kings."

These Roman associations of the pileus with liberty and republicanism were carried forward to the 18th century, until when the pileus was confused with the Phrygian cap, then becoming a symbol of those values in the wake of Medieval Italian uses of the Phrygian cap, most notably in Venice..

In Venice, the Phrygian cap was used by the Doge instead of a crown as a symbol of Republican liberty, from the Middle Ages until 1797. The symbol of Libertas as a female figure holding the Phrygian cap upon a spear appeared in the 1500s in the Apotheosis of Venice, a major painting by Paolo Veronese in the Ducal palace, iconography that would later be reused in French and American art and coinage.

France's bonnet rouge

In revolutionary France In 1675, the anti-tax and anti-nobility Stamp-Paper revolt erupted in Brittany and north-western France, where it became known as the bonnets rouges uprising after the blue or red caps worn by the insurgents. Although the insurgents are not known to have preferred any particular style of cap, the name and color stuck as a symbol of revolt against the nobility and establishment. Robespierre would later object to the color but was ignored.

The use of a Phrygian-style cap as a symbol of revolutionary France is first documented in May 1790, at a festival in Troyes, adorning a statue representing the nation, and at Lyon, on a lance carried by the goddess Libertas.Albert Mathiez, Les Origines des cultures révolutionnaires, 1789–1792 (Paris 1904:34). To this day the national allegory of France, Marianne, is shown wearing a red Phrygian cap.Richard Wrigley, "Transformations of a revolutionary emblem: The Liberty Cap in the French Revolution, French History 11(2) 1997:131–169.