"Thy city, which is full Of envy so that now the sack runs over"

(Canto 6, lines 49-50)

To expose and criticize the Florentian factional fighting, along with the idea that it was all due to envy, is one of the main themes of the Comedy, and it is directly touched upon here for the first time. The clan rivalries in Florence had a long history, which mostly took the form of opposition between the political groupings of the Guelfs and Ghibellines, which divided all of Italy in two during the 12th to 14th centuries. The two groupings arose after the death in 1125 of Henry V, last Holy Roman Emperor of the Salian dynasty. The Guelfs supported Henry's descendant Lothair of Supplinburg, the Duke of Saxony, while the Ghibellines supported his rival Frederick of Hohenstaufen, Duke of Swabia. The Pope in Rome sided with the Guelfs. After many years of warfare, the positions of the two groupings evolved into one supporting the city republics and the Pope (the Guelfs) and the other supporting the monarchy and the nobility (Ghibellines), which further developed into inter-city warfare (like when Florence was dominated by the Guelfs and the Ghibellines controlled Milan). Later, there arose not only rivalry within each city (Florence itself was divided between Guelfs and Ghibellines after 1215), but opposition arose within the parties as well, most famously exemplified by the division of Florentine Guelfs into the Black and White parties during the late 13th and early 14th century. The Black party was led by Corso Donati and were regarded as more radical, the Whites' leader was Vieri de Cerchi, and they were rather more moderate. Dante himself belonged to the Whites.