# Quaternion Eagle

The Quaternion Eagle (German: Quaternionenadler; Italian: aquila quaternione), also known as the Imperial Quaternion Eagle (German: Quaternionen-Reichsadler) or simply Imperial Eagle (German: Reichsadler), was an informal coat of arms of the Holy Roman Empire.
Introduced around 1510 by Hans Burgkmair, the Quaternion Eagle mixed two pre-existing concepts: the Imperial Quaternions and the Imperial Eagle (double-headed eagle).

## History
### Background

The so-called imperial quaternions (German: Quaternionen der Reichsverfassung, lit. 'quaternions of the imperial constitution'; from Latin: quaterniō, lit. 'group of four soldiers') were a conventional representation of the Imperial States of the Holy Roman Empire which first became current in the 15th century and was extremely popular during the 16th century.
Apart from the highest tiers of the emperor, kings, prince-bishops and the prince electors, the estates are represented in groups of four. The number of quaternions was usually ten, in descending order of precedence:
* Dukes (Duces),
* Margraves (Marchiones),
* Landgraves (Comites Provinciales),
* Burggraves (Comites Castrenses),
* Counts (Comites),
* Knights (Milites),
* Noblemen (Liberi),
* Cities (Metropoles),
* Villages (Villae),
* Peasants (Rustici).
The list could be shortened or expanded, by the mid-16th century to as many as 45.
It is likely that this system was first introduced under Emperor Sigismund, who is assumed to have commissioned the frescoes in Frankfurt city hall in 1414.
As has been noted from an early time, this representation of the "imperial constitution" does not in fact represent the actual constitution of the Holy Roman Empire, as some imperial cities appear as "villages" or even "peasants" and the Burggrave of Stromburg was an unknown entity even at the time. The representation of imperial subjects is also far from complete. The "imperial quaternions" are, rather, a more or less random selection intended to represent pars pro toto the structure of the imperial constitution.

### Coat of the Empire

Over its long history, the Holy Roman Empire used many different heraldic forms, representing its numerous internal divisions. One rendition of the coat of the empire was the Quaternion Eagle, printed by David de Negker of Augsburg after a 1510 woodcut by Hans Burgkmair.
Named after the imperial quaternions, it showed a selection of 56 shields of various Imperial States in groups of four on the feathers of a double-headed eagle (the imperial eagle's remiges), supporting, in place of a shield, Christ on the Cross.
The four Spiritual (geistliche) Electors: Trier, Cöln (Cologne), Mentz (Mainz), Potestat zu Rom (Holy See)
The four Mundane Temporal (weltliche): (Bohemia), Pfaltz (Palatinate), Sachsen (Saxony), Brandenburg
Seill ("pillars"): Braunschweig, Bairn (Bayern, Bavaria), Swaben (Schwaben, Swabia), Lutring (Lothringen, Lotharingia)
Vicarii ("vicars"): Brabandt (Brabant), n.Sachsen (Niedersachsen, Lower Saxony), Westerreich (Westrich), Schlessi (Schlesien, Silesia)
Marggraven (margraves): Merchern (Mähren, Moravia), Brandenburg, Meichssen (Meißen), Baden
Lantgraven (landgraves): Thüringen (Thuringia), Elsaß, Hessen, Leuchtenberg
Burggraven (burggraves): Nürnberg (Nuremberg), Maidburg (Hardegg-Maidburg), Reineck (Rieneck), Stramberg (Stromberg)
Graven (counts): Cleve, Saphoy (Savoyen, Savoy), Swartzburg (Schwarzburg), Zilli (Celje)
Semperfreie (nobles): Lintpurg (Limpurg), Westerburg, Thussis (Thusis), Alwalden (Aldenwalden)
Ritter (knights): Anndelaw (Andlau), Weissenbach, Frawnberg (Fraunberg), Strundeck ("Stromdeck")
Stett (cities): Augspurg (Augsburg), Metz, Ach (Aachen), Lubeck (Lübeck)
Dörfer (villages): Bamberg, Ulm, Hagenaw (Hagenau), Sletstat (Schlettstatt)
Bauern (peasants): Cöln (Köln, Cologne), Regenspurg (Regensburg), Costnitz, Salzburg
Birg (castles): Magdaburg (Magdeburg), Lützelburg, Rottenburg, Aldenburg
Twelve vertical quaternions were shown under them, as follows — eight dukes being divided into two quaternions called "pillars" and "vicars", respectively:
The depiction also appeared on the Imperial Eagle beaker.

## Imperial Eagle beaker

An Imperial Eagle beaker (German: Reichsadlerhumpen), or eagle glass, was a popular drinking vessel from the 16th until the late 18th century in the Holy Roman Empire. The enamelled glass was decorated with a double-headed eagle, usually in the shape of a Quaternion Eagle. The Reichsadler means "Imperial Eagle" or double-headed eagle which was the emblem of the empire, while "humpen" refers to a cylindrical drinking glass. These beakers became the essential medium to represent the most popular explanatory model for the emergence of the Empire: the quaternion theory as represented by Hans Burgkmair.
The Imperial Eagle beakers showed the solidarity between the owner and the Empire and were very popular because of their decorativeness and luminous colors. But these drinking vessels were also valued for their generous size. Equally popular were the electors' beakers, which were decorated with illustrations of the emperor and electors as the most important representatives of the Empire.