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THE conflict with infidelity and heresy had three principal
theatres: fields of battle, tribunals, and councils. Upon fields
of battle the enemies of the Church were dealt with accord-
ing to the laws of war; before the tribunals, the penal code
was applied to them; in the councils, the procedure against
them was by definitions and regulations. Among the wars
undertaken for the glory of God the crusades occupy a
peculiar place, and the tribunals have their highest expres-
sion in the Inquisition. We shall treat successively of the
crusades; of the Inquisition, in which we shall include wars
waged by the papacy against its enemies in Europe; and
lastly of the councils.