Guelph a member of one of two great factions in Italian medieval politics, traditionally supporting the Pope against the Holy Roman emperor (supported by the Ghibellines). The name comes through Italian Guelfo from Middle High German Welf, the name of the founder of one of the two great rival dynasties in the Holy Roman Empire, a princely family of Swabian origin from which the British royal house is descended through George I.

The name Welf is believed to have been adopted into political use in Italy from its reputed use as a war cry (at the battle of Weinsburg in 1140) by partisans of Henry the Lion, Duke of Bavaria, who belonged to this family, and fought against the Emperor Conrad III; it was thus adopted as a name for the adversaries of the Hohenstaufen emperors.

Guelph Political faction in medieval Italy, opposed to the Ghibelline. The two factions were linked to rival families contending for the Holy Roman Empire in the 12th century. In 1198, Otto IV (a Guelph) became Holy Roman Emperor. In the battle for control of Italy, the Guelphs took the side of the papacy, while the Ghibellines backed the emperor Frederick II. In 1268, the Guelphs defeated the Ghibellines at Tagliacozzo, but the feud smouldered on. See also Hohenstaufen

Ghibelline Political faction in 13th-century Italy that supported the Hohenstaufen dynasty of the Holy Roman Empire and opposed the pro-papal Guelphs. During the struggles between Frederick II and the Popes in the mid-13th century, Ghibellines came to designate those on the Imperial side. Defeated by the Guelphs in 1268, the family went into decline.

Ghibelline a member of one of the two great political factions in Italian medieval politics, traditionally supporting the Holy Roman emperor against the Pope and his supporters, the Guelphs, during the long struggle between the papacy and the Empire. The name may come ultimately from German Waiblingen, an estate belonging to Hohenstaufen emperors.