They also retained something of the old Roman civilization, and Roman
legal usages and some knowledge of Roman law never quite died out. In
other respects they much resembled mediaeval cities elsewhere.

REESTABLISHMENT OF THE HOLY ROMAN EMPIRE. After the disintegration of
Charlemagne's empire, the portion of it now known as Germany broke up into
fragments, largely independent of one another, and full of fight and
pride. The result there was continual and pitiless warfare. This, coupled
with the raids of the Northmen along the northern coast and the Magyars on
the east, led to the election of a king in 919 (Henry the Fowler) who
could establish some semblance of unity and order. By 961 the German
duchies and small principalities had been so consolidated that a
succeeding king (Otto I) felt himself able to attempt to reestablish the
Holy Roman Empire by subjugating Italy and annexing it as an appendage
under German rule.

He descended into Italy (961), subjugated the cities, overthrew the
Papacy, created a pope to his liking, and reestablished the old Empire, in
name at least. For a century the German rule was nominal, but with the
outbreak of the conflict in the eleventh century between king and pope
over the question of which one should invest the bishops with their
authority (known as the _investiture conflict_, 1075-1122), Pope Gregory
VII humbled the German king (Henry IV) at Canossa (1077) and won a partial
success. Then followed repeated invasions of Italy, and a century and a
half of conflicts between pope and king before the dream of universal
empire under a German feudal king ended in disaster, and Italy was freed
from Teutonic rule.

[Illustration: FIG. 54, THE CITY-STATES OF NORTHERN ITALY
All of the cities in the valley of the Po, except Turin, Pavia, and