[1] He was summoned before the Diet of Pavia for having dispossessed
a noble of his feud.

Having founded their liberties upon the episcopal presidency, the cities
now proceeded to claim the right of choosing their own Bishops. They
refused the prelates sent them by the Emperor, and demanded an election
by the Chapters of each town. This privilege was virtually won when the
war of Investitures broke out in 1073. After the death of Gregory VI. in
1046, the Emperors resolved to enforce their right of nominating the
Popes. The two first prelates imposed on Rome, Clement II. and Damatus
II., died under suspicion of poison. Thus the Roman people refused a
foreign Pope, as the Lombards had rejected the bishops sent to rule
them. The next Popes, Leo IX. and Victor II., were persuaded by
Hildebrand, who now appears upon the stage, to undergo a second
election at Rome by the clergy and the people. They escaped
assassination. But the fifth German, Stephen X., again died suddenly;
and now the formidable monk of Soana felt himself powerful enough to
cause the election of his own candidate, Nicholas II. A Lateran council,
inspired by Hildebrand, transferred the election of Popes to the
Cardinals, approved by the clergy and people of Rome, and confirmed the
privilege of the cities to choose their bishops, subject to Papal
ratification. In 1073 Hildebrand assumed the tiara as Gregory VII., and
declared a war that lasted more than forty years against the Empire. At
its close in 1122 the Church and the Empire were counterposed as
mutually exclusive autocracies, the one claiming illimitable spiritual
sway, the other recognized as no less illimitably paramount in civil
society. From the principles raised by Hildebrand and contested in the
struggles of this duel, we may date those new conceptions of the two
chief powers of Christendom which found final expression in the
theocratic philosophy of the _Summa_ and the imperial absolutism of the
_De Monarchia_. Meanwhile the Empire and the Papacy, while trying their
force against each other, had proved to Italy their essential weakness.
What they gained as ideas, controlling the speculations of the next two
centuries, they lost as potentates in the peninsula. It was impossible
for either Pope or Emperor to carry on the war without bidding for the
support of the cities; and therefore, at the end of the struggle, the
free burghs found themselves strengthened at the expense of both powers.