Guelphs and Ghibellines, opposing political factions in Germany and in Italy during the later Middle Ages. The names were used to designate the papal (Guelph) party and the imperial (Ghibelline) party during the long struggle between popes and emperors, and they were also used in connection with the rivalry of two princely houses of Germany, the Welfs or Guelphs, who were dukes of Saxony and Bavaria, and the Hohenstaufen (the name Ghibelline is supposedly derived from Waiblingen, a Hohenstaufen castle). The rivalry between the German families, both of which had large holdings in Swabia, dates from their rise to power under Holy Roman Emperor Henry IV. The struggle began in earnest with Henry the Proud and his son and successor, Henry the Lion, and last flared up with the election of Otto IV as Holy Roman emperor. In Italy the party names were perpetuated by two rival factions that for many years plunged the country into internal warfare. The names were first used in 13th-century Florence to designate the supporters of Otto IV (a Guelph) and the Hohenstaufen Frederick II (a Ghibelline). The terms, however, soon lost their original significance. Among the Ghibellines were Ezzelino da Romano, Castruccio Castracani, Della Scala of Verona, the Montefeltro family of Urbino, and the Visconti family of Milan (although Milan itself was Guelph). Unlike the noble families, towns seldom had fixed party loyalties, although Milan, Florence, and Genoa were usually Guelph; Cremona, Pisa, and Arezzo were usually Ghibelline. Venice remained neutral. In Rome the Ghibellines were represented by the pope's enemies, notably the Colonna family, and by the republicans. In S Italy the terms were rarely used, although the Angevin kings of Naples were strongly Guelph. In Florence, after the Ghibellines had finally been expelled in the late 13th cent., the Guelphs soon divided into Blacks and Whites. By the 15th cent. the names fell into disuse. At no time did either party clearly represent any particular political doctrine or social class.