Frederick I (1123-1190), or Frederick Barbarossa, was Holy Roman Emperor from 1152 to 1190. He was one of the greatest monarchs of medieval Germany, and his strong rule set many patterns of future development.

The son of Duke Frederick II of Swabia, Frederick I was the nephew of Emperor Conrad III of the Hohenstaufen family. Frederick's mother, Judith, however, was a Welf, the sister of Henry the Proud, Duke of Saxony and Bavaria. Thus in his own person he united these rival families, whose feuding had torn Germany apart for some decades. He was brave, intelligent, and chivalrous and, in his later years, wore a long red beard, hence his name of Barbarossa, or Red Beard.

After Frederick was elected king of Germany in 1152, his first task was to negotiate a settlement with the Welf family in the person of his cousin Henry the Lion, Duke of Saxony. By 1156 an...