A Medieval Mess
In 12th century Europe, two entities competed for absolute power over the continent, the emperor and the pope, who used the argument over who got to appoint parish priests as an excuse to vie for control of Europe. The terms that came to describe Italian supporters of the emperor and Italian supporters of the pope actually stemmed from a German conflict over imperial succession.
In the 12th century, the German throne of the Holy Roman Emperor sat empty. Otto IV’s family, the Welf dynasty of Bavaria, fought for it against the lords of Waiblingen, where the house of Swabia ruled under the Hohenstaufen dynasty.
The names were corrupted in Italian to Guelf and Ghibelline, respectively, and when the Hohenstaufens came out winners with Frederick Barbarossa being crowned emperor, the Ghibellines stuck as the supporters of the emperor while the Guelfs became the party that backed the pope.
In Italy, the issue was all about who got to be in charge: the old nobility, who as Ghibellines favored the imperial promise of a return to feudalism and hence their own power, or the Guelf merchant-and-banking middle class, who supported the pope and his free-trade attitudes. While these terms did mean something regarding which faction, nobles or merchants, controlled any one city, they were used mainly to define one city in terms of its opposition to rival cities.
Though it’s admittedly not the perfect measure, you can sometimes tell which a city was, at least at any given time, by looking at the battlements of the medieval town hall: The Guelfs favored squared-off crenellations and the Ghibellines swallowtail ones.
Exceptions to this are Siena’s Palazzo Pubblico, which was built with blocky battlements during the briefly Guelf period of the Council of Nine, and Florence’s Palazzo Vecchio, which confusingly sports both kinds.
So if your rivals were Ghibelline, you’d go Guelf, and if they turned Guelf for some reason, you usually swung around to Ghibelline pretty quickly. Although they all flip-flopped to some degree, Florence (plus Lucca, Arezzo, and Perugia) turned out Guelf, which made rivals Pisa, Pistoia, and Siena Ghibelline.
The Guelf/Ghibelline conflict not only spawned intercity warfare but also sparked intracity strife between rival factions. The most famous intracity conflict occurred in Florence in the 13th century, when powerful warring clans each took up arms and called in alliances, and the city split into Guelf and Ghibelline parties, under which names the parties waged a decades-long struggle over who’d control the city government.
In Florence, when the Guelfs finally won in the late 13th century, they further divided into two factions, the Blacks (Guelfs) and the Whites (Ghibellines, but only because they hated Pope Boniface VIII). When the Blacks came out on top, they exiled the Whites, among whom was a Florentine White Guelf ambassador named Dante who lived the rest of his life in exile, perfecting his poetry.
Florence began to enjoy, at the turn of the 14th century when the Black Guelfs finally came out victorious, a fairly stable republican rule—still of the old assembly system called now the Signoria, a ruling council elected from the major guilds. Florence slowly expanded its power, first allying with Prato, then conquering Pistoia, and by 1406 adding Volterra, Arezzo, and Pisa to the cities under its rule.
As the major guilds accrued more and more power and the top merchants seized control of Florence, the minor guilds and lesser merchants looked to one of the few renegade merchant families sympathetic to their plight. It was an upstart family that, with a bit of luck, had recently risen from virtual anonymity to become one of the most successful banking houses in the city. It was a clan without a particularly distinguished pedigree, a fact that kept them from being fully accepted by the major guild leaders who came from old Florentine families.
They called themselves the Medici.