Keeping Kings in Check 83Th e Conduct of Wars
It has been observed that just- war doctrine had no specifi c rules about the
conduct of wars, but only a general prohibition against purely gratuitous vio-
lence. Here, as in other areas of medieval international relations, canon law-
yers made an important contribution. Raymond of Peñaforte, for example,
pondered such questions as the use of catapults and archers in war. He also
considered crimes committed during war, such as robbery, rape, and arson.
Aquinas, in scattered places in his writings, touched on questions of proper
military conduct, insisting, for example, at least in general terms, on proper
discipline and morale among soldiers. He duly condemned desertion and ap-
proved of the wearing of insignia by soldiers to facilitate recognition.
One issue on which there was a division of opinion among writers was
the question of keeping faith with an unjust enemy, for example in the
making of truces. Some writers forbade entering into any agreements with
an unjust enemy in the fi rst place. Others held such agreements to be
permissible— and that, if they were made, they must be faithfully kept. It
should be appreciated, though, that what was at stake here was an applica-
tion of the general natural-law duty of good faith to one’s fellow man and
not really a rule about the conduct of war per se. Th e prevailing conclusion
was that the general natural- law duty of good faith retained its force even
during time of war.
To some extent, the church took direct steps to mitigate the horrors of
war. Th is was done in several ways. One was through something called the
Peace of God, which was directed toward the protection of various classes of
persons from attack— women and children, clerics, peasants, and unarmed
noncombatants in general. Gratian’s Decretum, the great canon law com-
mentary of the mid- twelft h century, had several provisions to this eff ect, as
did the Th ird Lateran Council of 1179. In addition, there was the Truce of
God, which restricted the time periods in which wars could be waged. War-
fare in the period of the week from Th ursday to Sunday came to be prohib-
ited in canon law.
In one notable instance, there was a restriction on specifi ed types of weap-
onry. Th is was a canon of the Second Lateran Council, held by the Catholic
Church in 1139, which condemned “that murderous art of crossbowmen and
archers, which is hateful to God” and prohibited the employment of these