In central Europe, the German king Otto I (r. 936–973) defeated many other lords to build his power from his original base in Saxony. Otto garnered financial support from church leaders and also asserted the right to control ecclesiastical appointments. This practice, later known as lay investiture, created a grave crisis between the church and the monarchy in the eleventh century (see "Emperor Versus Pope").

In 955, Otto I inflicted a crushing defeat on the Magyars in the Battle of Lechfeld. In 962, he used this victory to have himself crowned emperor by the pope. Though it was not exactly clear what Otto was the emperor of, by the eleventh century, people were increasingly using the term Holy Roman Empire to refer to a loose confederation of principalities, duchies, cities, bishoprics, and other types of regional governments stretching from Denmark to Rome and from Burgundy to Poland (Map 9.2).

In this large area of central Europe and northern Italy, the Holy Roman emperors shared power with princes, dukes, archbishops, counts, bishops, abbots, and cities. The office of emperor remained an elected one, though the electors numbered seven — four secular rulers of large territories within the empire and three archbishops.

None of Otto’s successors were as forceful as he had been, and by the first half of the twelfth century, civil wars wracked the empire. The electors decided the only alternative to continued chaos was the selection of a strong ruler. They chose Frederick Barbarossa of the house of Hohenstaufen (HOH-uhn-shtow-fuhn) (r. 1152–1190). Like William the Conqueror in England and Philip in France, Frederick required vassals to take an oath of allegiance to him as emperor and appointed officials to exercise full imperial authority over local communities.

Between 1154 and 1188, Frederick made six military expeditions into Italy in an effort to assert his imperial rights over the increasingly wealthy towns of northern Italy. While he initially made significant conquests, the Italian cities formed leagues to oppose him and also allied with the papacy. In 1176, Frederick suffered a crushing defeat at Legnano (see Map 9.2). Frederick was forced to recognize the municipal autonomy of the northern Italian cities and the pope’s sovereignty in central Italy. His campaigns in Italy took him away from the parts of the empire north of the Alps, and regional rulers there reasserted their authority toward the end of Frederick’s reign and in the reigns of his successors. Thus, in contrast to France and England, Germany did not become a unified state in the Middle Ages and would not until the nineteenth century.