At the end of the fifteenth century the normal state among Christians was assumed to be peace, tempered by a readiness to repel the infidel. In practice nothing was more likely than war among Christians and, in order to leave them free to pursue it, overtures of peace to the Turk.

Chivalric writers still taught that war could be glorious, the scientific approach of Italian theorists lost sight of its horrors in deep interest, and both points of view admired the successful captain—one for his bravery, his prouesse, the other for the mark on events of his genius and energy, his virtù. The first thought war legitimate because it was noble, the other because force was an obvious and legitimate branch of negotiation.

The Church also, by supporting the institutions of chivalry and the knightly orders, had blessed weapons that were not always to be used against the oppressor or the infidel, and by admitting that it was permissible to wage a just war, she had in effect sanctioned all wars. The criteria of a just war, it was generally agreed, were that it should only be waged on the authority of a superior, for a just cause and with righteous intent, and the satisfaction of these conditions was not hard save to the most recalcitrant conscience. The Church, too, needed war to support her authority and punish those who defied it. And she was partly responsible for the view that in great causes war was a divine judgment, an extension of the judicial duel, where two armies instead of two rival champions fought to decide who was in the right.