joining the Catholic communion, whereby they strengthened the hands of
Rome and excluded themselves from tyrannizing in the last resort over
the growing independence of the Papal See. The causes of their
conversion from Arianism to orthodox Latin Christianity are buried in
obscurity. But it is probable that they were driven to this measure by
the rebelliousness of their great vassals and the necessity of resting
for support upon the indigenous populations they had subjugated. Rome,
profiting by the errors and the weakness of her antagonists, extended
her spiritual dominion by enforcing sacraments, ordeals, and appeals to
ecclesiastical tribunals, organized her hierarchy under Gregory the
Great, and lost no opportunity of enriching and aggrandizing her
bishoprics. In 718 she shook off the yoke of Byzantium by repelling the
heresies of Leo the Isaurian; and when this insurrection menaced her
with the domestic tyranny of the Lombard Kings, who possessed themselves
of Ravenna in 728, she called the Franks to her aid against the now
powerful realm. Stephen II. journeyed in 753 to Gaul, named Pippin
Patrician of Rome, and invited him to the conquest of Italy. In the war
that followed, the Franks subdued the Lombards, and Charles the Great
was invested with their kingdom and crowned Emperor in 800 by Leo III.
at Rome.

The famous compact between Charles the Great and the Pope was in effect
a ratification of the existing state of things. The new Emperor took for
himself and converted into a Frankish Kingdom all the provinces that had
been wrested from the Lombards. He relinquished to the Papacy Rome with
its patrimony, the portions of Spoleto and Benevento that had already
yielded to the See of S. Peter, the southern provinces that owned the
nominal ascendency of Byzantium, the islands and the cities of the
Exarchate and Pentapolis which formed no part of the Lombard conquest.
By this stipulation no real temporal power was accorded to the Papacy,