“Something else that must very much be preserved in public affairs is the justice of warfare. There are two types of conflict: the one proceeds by debate, the other by force. Since the former is the proper concern of a man, but the latter of beasts, one should only resort to the latter if one may not employ the former. Wars, then, ought to be undertaken for this purpose, that we may live in peace, without injustice; and once victory has been secured, those who were not cruel or savage in warfare should be spared.” Marcus Tullius Cicero, On Duties I. 34-35. eds. and trans. M.T. Griffin and E.M. Atkins (Cambridge 1991), pp. 14-15.
Cicero wrote that humanity’s proper concern is debate, not physical conflict. This reflects an understanding of human beings as more than mere animals. However, he recognized that wars were sometimes necessary to keep the peace and preserve justice. He also pointed out that Roman law prescribed the correct manner by which to wage war.
“Indeed, a fair code of warfare has been drawn up, in full accordance with religious scruple, in the fetial laws of the Roman people. From this we can grasp that no war is just unless it is waged after a formal demand for restoration, or unless it has been formally announced and declared beforehand. ” Cicero, On Duties I. 36, trans. Griffin and Atkins, pp. 15-16.
The “fetial laws” refers to a group of men, known as the fetiales, who oversaw foreign relations. This group determined the legitimacy of declaring and waging war. Then they gave an ultimatum for recompense to the potential enemy as Cicero described above.