THE Guelphs and Ghibellines were factions supporting, respectively, the Pope and the Holy Roman Emperor in central and northern Italy during the 12th and 13th centuries […] The struggle for power between the Papacy and the Holy Roman Empire had arisen with the Investiture Conflict which began in 1075 and ended with the Concordat of Worms in 1122, but the division between Guelphs and Ghibellines in Italy persisted to the 15th century.
Ghibellines were the imperial party, while the Guelphs supported the Pope. Broadly speaking, Guelphs tended to come from wealthy mercantile families, whereas Ghibellines were predominantly those whose wealth was based on agricultural estates.
It must be noted that contemporaries did not use the terms Guelphs and Ghibellines […] with the names “church party” and “imperial party” preferred in some areas.
The division between Guelphs and Ghibellines was especially important in Florence […] By 1300 Florence was 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.
During the 12th and 13th centuries, armies of the Ghibelline communes usually adopted the war banner of the Holy Roman Empire—white cross on a red field—as their own. Guelph armies usually reversed the colours—red cross on white.