Joseph Strayer, Western Europe in the Middle Ages (1955)
“ Force had to be used to overcome immediate opposition, but the Carolingians were wise enough to realize that force alone would never give them a secure position. They had to gain the loyalty of their subjects by giving them a common set of ideals, and the only ideals which could be accepted by all the inhabitants of the West were those of Christianity. Therefore, the Carolingians consistently and energetically supported missions to the pagans and reform movements among the nominally Christian inhabitants of their empire. ”
