The Reichsadler ("Imperial Eagle") was the heraldic eagle, derived from the Roman eagle standard, used by the Holy Roman Emperors and in modern coats of arms of Germany, including those of the Second German Empire (1871–1918), the Weimar Republic (1919–1933) and the "Third Reich" (Nazi Germany, 1933–1945).
The same design has remained in use by the Federal Republic of Germany since 1945, but under a different name, now called Bundesadler ("Federal Eagle").
The Reichsadler can be traced back to the banner of the Holy Roman Empire, when the eagle was the insignia of Imperial power as distinguished from the Imperial states. It was meant to embody the reference to the Roman tradition (translatio imperii), similar to the double-headed eagle used by the Palaiologi emperors of the Byzantine Empire or the tsars of Russia (see coat of arms of Russia).
A double-headed eagle was attributed to Frederick II of Hohenstaufen in the Chronica Majora by Matthew Paris about 1250, and also appeared on the seal of the Imperial city of Kaiserswerth in the 13th century. The Reichsadler was widely used by Imperial cities such as Lübeck, Besançon and Cheb to underline their Imperial immediacy. The Teutonic Order under Hermann von Salza had the privilege to display the Imperial eagle in their coat of arms, granted by Emperor Frederick II. The black eagle was later adopted when the Teutonic State was transformed into the Duchy of Prussia in 1525.
Sigismund of Luxembourg used a black double-headed eagle after he was crowned Emperor in 1433, while the single-head eagle remained an ensign of the elected King of the Romans and Emperor-to-be. In 1804, Holy Roman Emperor Francis II established the Austrian Empire from the lands of the Habsburg Monarchy, and adopted the double-headed eagle, aggrandized by an inescutcheon emblem of the House of Habsburg-Lorraine and the Order of the Golden Fleece, as its coat of arms; the Holy Roman Empire was subsequently dissolved in 1806. Since 1919 the coat of arms of Austria has depicted a single-headed eagle. Although not a national symbol in the modern sense, the Reichsadler evoked sentiments of loyalty to the empire.
During the revolutions of 1848 in the German states, some attempts were made to reimplement the Reichsadler as a symbol of national unity. These ideas were taken up again when a single-head eagle with a Prussian inescutcheon became the insignia of Bismarcks's kleindeutsche Lösung in the shape of the German Empire in 1871. After World War I the Weimar Republic under President Friedrich Ebert assumed a plain version of the Reichsadler, which stayed in use until 1935.
During Nazi rule, a stylised eagle combined with the Nazi swastika was made the national emblem (Hoheitszeichen) by order of Adolf Hitler in 1935. Despite its mediæval origin, the term "Reichsadler" in common English understanding is mostly associated with this specific Nazi era version. The Nazi Party had used a very similar symbol for itself, called the Parteiadler ("Party's eagle"). These two insignia can be distinguished as the Reichsadler looks to its right shoulder whereas the Parteiadler looks to its left shoulder.
After World War II the Federal Republic of Germany re-implemented the eagle used by the Weimar Republic by enactment of President Theodor Heuss in 1950.