The eagle is used in heraldry as a charge, as a supporter, and as a crest. Sometimes just the headless body ("sans head" eagle) or the head replaced with another symbol, as well as parts of the eagle, such as its head, wing or leg, are used as a charge or crest.
The eagle with its keen eyes symbolized perspicacity, courage, strength and immortality, but is also considered "king of the skies" and messenger of the highest Gods. With these attributed qualities the eagle became a symbol of power and strength in Ancient Rome. Mythologically, it has been connected by the Greeks with the God Zeus, by the Romans with Jupiter, by the Germanic tribes with Odin, by the Judeo-Christian scriptures with those who hope in God (Isa 40:31), and in Christian art with Saint John the Evangelist.
The eagle as a symbol has a history much longer than that of heraldry itself. In Ancient Egypt, the falcon was the symbol of Horus, and in Roman polytheism of Jupiter. An eagle appears on the battle standard of Cyrus the Great in Persia, around 540 BC. The eagle as a "heraldic animal" of the Roman Republic was introduced in 102 BC by consul Gaius Marius. According to Islamic tradition, the Black Standard of Muhammad was known as راية العُقاب rāyat al-`uqāb "banner of the eagle" (even though it did not depict an eagle and was solid black). In Christian symbolism the four living creatures of scripture (a man, an ox, a lion, and an eagle) have traditionally been associated with the Four Evangelists. The eagle is the symbol of Saint John the Evangelist.
In medieval and modern heraldry eagles are often said to indicate that the armiger (person bearing the arms) was courageous, a man of action and judicious. Where an eagle's wings were spread ("displayed") it was said to indicate the bearer's role as a protector.
In the same way that a lion is considered the king of beasts, the eagle is regarded as the pre-eminent bird in heraldry. It has been more widely used and more highly regarded in Continental European heraldry than in English heraldry. For instance, in the roll of Henry III of England (reigned 1216–1272) there are only three eagles.
Media related to examples of heraldic eagles at Wikimedia Commons
The depiction of the heraldic eagle is subject to a great range of variation in style. The eagle was far more common in continental European—particularly German—than English heraldry, and it most frequently appears sable, often armed and langued gules, that is, black with red claws, beak and tongue. In its relatively few instances in Gallo-British heraldry, the outermost feathers are typically longer and point upward.
An eagle can appear either single- or double-headed. On at least one occasion a three-headed eagle is seen. Additionally, Reinmar von Zweter fashioned the wing bones of his eagle into a second and third head.
The informal term "spread eagle" is derived from a heraldic depiction of an eagle displayed (i.e. upright with both wings and both legs all outstretched). According to Hugh Clark, An Introduction to Heraldry, the term spread eagle refers to "an eagle with two heads, displayed," but this distinction has apparently been lost in modern usage. Most of the eagles used as emblems of various monarchs and states are displayed, including those on the coats of arms of Germany, Poland, and Romania and the United States.
The Aquila was the eagle standard of a Roman legion, carried by a special grade legionary known as an Aquilifer. One eagle standard was carried by each legion. Pliny the Elder (H.N. x.16) enumerates five animals displayed on Roman military ensigns: the eagle, the wolf, the minotaur, the horse, and the boar. In the second consulship of Gaius Marius (104 BC) the four quadrupeds were laid aside as standards, the eagle being alone retained. It was made of silver, or bronze, with outstretched wings, but was probably of a relatively small size, since a standard-bearer (signifer) under Julius Caesar is said in circumstances of danger to have wrenched the eagle from its staff and concealed it in the folds of his girdle. Under the later emperors the eagle was carried with the legion, a legion being on that account sometimes called aquila (Hirt. Bell. Hisp. 30). Each cohort had for its own ensign the serpent or dragon, which was woven on a square piece of cloth textilis anguis, elevated on a gilt staff, to which a cross-bar was adapted for the purpose, and carried by the draconarius.
Eastern imperial eagles
The double-headed eagle became the symbol of the Emperor Michael VIII Palaiologos. Palaiologos recaptured Constantinople from the Crusaders in 1261 and adopted the double-headed eagle as his symbol of the dynasty's interests in both Asia and Europe. It represented looking towards the East (Asia Minor, traditional power center of the Byzantine-government in exile after the IVth Crusade) and the West (newly reconquered land in Europe) centered on Constantinople. The Byzantine double-headed eagle has been seen in late 13th century, certainly pre-dating the development of the same in western heraldry.
In Russia it was Ivan III of Russia who first assumed the two-headed eagle, when, in 1472, he married Sophia, daughter of Thomas Palæologus, and niece of Constantine XI, the last Emperor of Byzantium. The two heads symbolised the Eastern or Byzantine Empire and the Western or Roman Empire.
The Empire of Trebizond (1204–1461), one of the states created after the capture of Constantinople by the Fourth Crusade, used the emblem of the normal (single headed) eagle. The black eagle on yellow background is still used today in Greece by descendants of Pontian Greeks.
Holy Roman Empire
Charlemagne, a Frankish ruler and the first Holy Roman Emperor, died in 814, centuries before the introduction of heraldry. In later periods, a coat of arms attributed to Charlemagne shows half of the body of a single-head black eagle as the symbol of the German emperors next to a fleur-de-lis as the symbol of the kings of France on an impaled shield.
According to Carl-Alexander von Volborth the first instance of the use of an eagle as an heraldic charge is the Great Seal of the Margrave Leopold IV of Austria in 1136, which depicts him carrying a shield charged with an eagle. Also from about this time is a coin showing a single-headed eagle, minted in Maastricht (the Netherlands), dating from between 1172 and 1190 after contacts with the East via the Crusades. One Gilbert d'Aquila was granted Baronetcy of Pevensey by William after the Battle of Hastings. The family who held Pevensey castle and the newly formed Borough of Pevensey used the eagle symbol in the 11th century.
From the reign of Frederick Barbarossa in 1155 the single-headed eagle became a symbol of the Holy Roman Empire. The eagle was clearly derived from the Roman eagle and continues to be important in the heraldry of those areas once within the Holy Roman Empire. Within Germany the placement of one's arms in front of an eagle was indicative of princely rank under the Holy Roman Empire. The first mention of a double-headed eagle in the West dates from 1250 in a roll of arms of Matthew Paris for Emperor Frederick II.
The French Imperial Eagle or Aigle de drapeau (lit. "flag eagle") was a figure of an eagle on a staff carried into battle as a standard by the Grande Armée of Napoleon I during the Napoleonic Wars. Although they were presented with Regimental Colours, the regiments of Napoleon I tended to carry at their head the Imperial Eagle. This was the bronze sculpture of an eagle weighing 1.85 kg (4 lb), mounted on top of the blue regimental flagpole. They were made from six separately cast pieces and, when assembled, measured 310 mm (12 in) in height and 255 mm (10 in) in width. On the base would be the regiment's number or, in the case of the Guard, Garde Impériale. The eagle bore the same significance to French Imperial regiments as the colours did to British regiments - to lose the eagle would bring shame to the regiment, who had pledged to defend it to the death. Upon Napoleon's fall, the restored monarchy of Louis XVIII of France ordered all eagles to be destroyed and only a very small number escaped. When the former emperor returned to power in 1815 (known as the Hundred Days) he immediately had more eagles produced, although the quality did not match the originals. The workmanship was of a lesser quality and the main distinguishing changes had the new models with closed beaks and they were set in a more crouched posture.
Since 20 June 1782, the United States has used its national bird, the bald eagle, on its Great Seal; the choice was intended to at once recall the Roman Republic and be uniquely American (the bald eagle being indigenous to North America). The American Eagle has been a popular emblem throughout the life of the republic, with an eagle appearing in the flags and seals of the President, Navy, Marine Corps, Air Force, Justice Department, Defense Department, Postal Service, and other organizations, on various coins (such as the quarter dollar), and in various American corporate logos past and present, such as those of Case and American Eagle Outfitters.
In Spain the eagle, though it was first used by the Catholic monarchs as a symbol of Saint John the Evangelist, came to be associated with the regime of Francisco Franco and since 1981 has been removed from official usage.
In Arab nationalism, with the Egyptian Revolution of 1952, the eagle became the symbol of revolutionary Egypt, and was subsequently adopted by several other Arab states (the United Arab Emirates, Iraq, Libya, the partially recognised State of Palestine, and Yemen).
The eagle as a symbol of Saladin is disputed by archaeologists. The symbol of an eagle was found on the west wall of the Cairo Citadel (constructed by Saladin), and so is assumed by many to be his personal symbol. There is, however, little proof to defend this.
As a heraldic symbol identified with Arab nationalism, the Eagle of Saladin was subsequently adopted as the coats of arms of Iraq and Palestine. It has previously been the coat of arms of Libya, but later replaced by the Hawk of Quraish. The Hawk of Quraish was itself abandoned after the Libyan Civil War. The Eagle of Saladin was part of the coat of arms of South Yemen prior to that country's unification with North Yemen.
A wide variety of political entities across the world use an eagle in their official emblems. The variation among them is instructive, in that it reflects connections among various heraldic traditions. The following is just a sampling of these.
-  granted in 1957 to Waiblingen (kreis) The three heads symbolise the three former territories that were transformed into the district.
- Reinmar von Zweter's peculiar eagle is famously depicted in the Codex Manesse.
- Clark, Hugh (1892). An Introduction to Heraldry, 18th ed. (Revised by J. R. Planché). London: George Bell & Sons. First published 1775. ISBN 1-4325-3999-X
- See Festuson the Minotaur.
- Flor. iv.12
- Sidon. Apoll. Carm. v.409
- Themist. Orat. i. p1, xviii. p267, ed. Dindorf; Claudian, iv. Cons. Honor. 546; vi. Cons. Honor. 566
- Veget. de Re Mil. ii.13; compare Tac. Ann. i.18
- Eleni Kokkonis-Lambropoulos & Katerina Korres-Zografos (1997). Greek flags, arms and insignia (Ελληνικές Σημαίες, Σήματα-Εμβλήματα) (in Greek). E. Kokkonis-G. Tsiveriotis. p. 52. ISBN 960-7795-01-6.
- Deutsche Wappen - GERMAN NATIONAL ARMS
- Act 33/1981, 5 October (BOE No 250, 19 October 1981). Coat of arms of Spain (Spanish).
- Fox-Davies, A.C.; A Complete Guide to Heraldry, Bloomsbury Books, London, 1985
- Puttock, Colonel A.G.; Heraldry in Australia, Child & Associated Publishing Pty. Ltd. Frenchs Forest, 1988
- Volborth, Carl-Alexander von; Heraldry, Customs, Rules and Styles, New Orchard Editions, Poole, 1981