The Guelphs and Ghibellines were factions supporting, respectively, the Papacy and the Holy Roman Empire in Italy during the 12th century and 13th century. Broadly, Guelphs tended to come from wealthy mercantile families, while Ghibellines wealth came from landed estates. The struggle for power between the Papacy and the Holy Roman Empire had actually arisen with the investiture conflict of the 11th century.
Guelph (sometimes spelled Guelf ) is most likely an Italian form of Welf, the family of the dukes of Bavaria (including the namesake Welf, as well as Henry the Lion). The Welfs were said to have used the name as a rallying cry during the Battle of Weinsberg in 1140, in which the rival Hohenstaufens of Swabia (led at the time by Conrad III) used Waiblingen, the name of a castle, as their cry. Waiblingen became Ghibelline in Italian. The names were likely introduced to Italy during the reign of Frederick Barbarossa. While campaigning in Italy to expand imperial power there, the Lombard League and its supporters became known as Guelphs, while those who supported Frederick became known as Ghibellines. The Lombard League defeated Frederick at the Battle of Legnano in 1176.
At the beginning of the 13th century, Philip of Swabia and Otto of Brunswick were rivals for the throne. Philip was supported by the Ghibellines as a relative of Frederick I, while Otto was supported by the Guelphs. Philip’s heir, Frederick II, was an enemy of both Otto and the Papacy, and during Frederick’s reign the Guelphs became more strictly associated with the Papacy while the Ghibellines became supporters of the Empire. Frederick II also introduced this division to the Crusader States in Syria during the Sixth Crusade.
After the death of Frederick II in 1250 the Ghibellines were supported by Conrad IV and later Manfred, while the Guelphs were supported by Charles of Anjou. After the Hohenstaufen line went extinct with Conradin’s death in 1268, the Guelphs and Ghibellines became associated with individual families and cities, rather than the struggle between empire and papacy. The division between Guelphs and Ghibellines was especially important in Florence, although the two sides frequently rebelled against each other and took power in many of the other northern Italian cities as well. Essentially the two sides were now fighting either against German influence (in the case of the Guelphs), or against the temporal power of the Pope (in the case of the Ghibellines). In Florence and elsewhere the Guelphs usually included merchants and burghers, while the Ghibellines tended to be noblemen. They also adopted peculiar customs such as wearing a feather on a particular side of their hats, or cutting fruit a particular way, according to their affiliation.
By 1300 the Guelphs in Florence were fighting amongst themselves, and were divided into the Black Guelphs and the White Guelphs. The Blacks continued to support the Papacy, while the Whites were opposed to Papal influence, specifically the influence of Pope Boniface VIII. Dante was among the supporters of the White Guelphs, and in 1302 was exiled when the Black Guelphs took control of Florence. Those who were not connected to either side, or who had no connections to either Guelphs or Ghibellines, considered both factions unworthy of support. Emperor Henry VII was disgusted by supporters of both sides when he visited Italy in 1310, and in 1334 Pope Benedict XII threatened excommunication to anyone who used either name.
In the 16th century the Guelphs supported of Charles VIII of France during his invasion of Italy, while the Ghibellines were supporters of emperor Maximilian I. Cities and families used the names until Emperor Charles V firmly established imperial power in Italy in 1529.
Adapted from the 1911 Encyclopedia Britannica and the Catholic Encyclopedia.