Frederick I, known as Barbarossa (“Red Beard”), was King of the Romans from 1152 and Holy Roman Emperor from 1155 until his death in 1190. A member of the Hohenstaufen dynasty, he sought to restore imperial authority in Germany and Italy, reasserting claims of sovereignty over territories that had developed strong communal and episcopal autonomy.

In northern Italy, Frederick attempted to impose imperial jurisdiction over self-governing communes such as Milan. His campaigns provoked resistance and led to the formation of the Lombard League ⓘ in 1167. After suffering defeat at the Battle of Legnano in 1176, Frederick recognised communal liberties in the Peace of Constance (1183), while retaining nominal imperial overlordship.

Within the Empire, Frederick worked to stabilise relations between imperial authority and the German princes, balancing power through negotiation as much as through force. His reign coincided with ongoing tensions between secular rulers and papal authority, particularly over questions of investiture, jurisdiction, and sovereignty. Although not defined by the Investiture Controversy of the previous century, his policies continued to test the boundaries between imperial and ecclesiastical power.

In 1189 Frederick took the cross and led the German contingent of the Third Crusade. He drowned in Asia Minor in 1190, an event that reverberated widely across Europe.

Frederick’s reign represents a pivotal moment in the twelfth-century struggle to define the nature of sovereignty in Latin Christendom: whether imperial power was universal and hierarchical, or negotiated and limited by communal and ecclesiastical rights.