On earth the peace-giving function of the Emperor of the Heavens was exercised by the emperor ordained by God. The Empire was a federation of peoples led by the Emperor, a federation in which concordia provinciarum, harmony between the members, prevails…

For its fideles, the Holy Roman Empire was a zone in which peace prevailed. To have peace within the Empire it was necessary to fight the ‘infidel’, the ‘heathen’, the ‘heretic’. In his own interpretations of his office, the Emperor was the supreme defender and protector of the church.

– Friedrich Heer, The Holy Roman Empire