The role and function of the Imperial Diet evolved over the centuries, like the Empire itself, with the estates and separate territories increasing control of their own affairs at the expense of imperial power. Initially, there was neither a fixed time nor location for the Diet. It began as a convention of the
dukes of the old
Germanic tribes that formed the
Frankish kingdom when important decisions had to be made, probably based on the old Germanic law whereby each leader relied on the support of his leading men. In the early and high Middle Ages these assemblies were not yet institutionalized, but were held as needed at the decision of the king or emperor. They weren't called Diet yet, but
Hoftag (
court day). They were usually held in the imperial palaces
(Kaiserpfalz). For example, already under
Charlemagne during the
Saxon Wars, a Hoftag, according to the
Royal Frankish Annals, met at
Paderborn in 777 and determined laws over the subdued
Saxons and other tribes. In 803 Charlemagne, by then crowned as emperor of the Franks, issued the final version of the
Lex Saxonum. At the Diet of 919 in
Fritzlar the dukes elected the first
King of the Germans, who was a Saxon,
Henry the Fowler, thus overcoming the longstanding rivalry between Franks and Saxons and laying the foundation for the German realm. After the conquest of
Italy, the 1158
Diet of Roncaglia finalized four laws that would significantly alter the (never formally written)
constitution of the Empire, marking the beginning of the steady decline of the central power in favour of the local dukes. The
Golden Bull of 1356 cemented the concept of "territorial rule" (
Landesherrschaft), the largely independent rule of the dukes over their respective territories, and also limited the number of electors to seven. The Pope, contrary to modern myth, was never involved in the electoral process but only in the process of ratification and coronation of whomever the Prince-Electors chose. at the
Diet of Worms, 152119th-century painting by
Hermann Wislicenus Until the late 15th century the Diet was not formalized as an institution. Instead, the dukes and other princes would irregularly convene at the court of the emperor. These assemblies were usually referred to as
Hoftage (from German
Hof "court"). Only beginning in 1489 was the Diet called the
Reichstag, and it was formally divided into
collegia ("colleges"). Initially, the two colleges were of the
prince-electors and of the remaining dukes and princes. Later, the
imperial cities with
Imperial immediacy became oligarchic republics independent of a local ruler, subject only to the emperor himself, and managed to be accepted as third parties. Motions passed if two of the colleges approved. Generally, the princely and electoral colleges would agree with each other, rather than rely on the cities to make a decision, but the cities still had influence. Several attempts to reform the Empire and end its slow disintegration, starting with the
Diet of 1495, did not have much effect. In contrast, this process was hastened with the
Peace of Westphalia of 1648, which formally bound the emperor to accept all decisions made by the Diet, in effect depriving him of his few remaining powers. Nonetheless, the emperor still had substantial influence in the Diet. The
Habsburg emperors possessed a large number of votes, and even held command over the
Imperial Army if the Diet decided to raise it. it recognized the unity of the Holy Roman Empire and founded the
Imperial Chamber, the empire's supreme court. == Participants ==