War

War, which is armed conflict between countries ornations, may be sometimes lawful and without sin. Three conditionsare necessary for a justified war: (a) it must be waged by lawfulpublic authority in defense of the common good; (b) it must bewaged for a just cause; (c) it must be waged with the rightintention, not vengefully nor to inflict harm.

It is not lawful for bishops and other clerics to fightin a war; such action is not in harmony with their place and theirduties.

Ambushes are strategems of war; they are part of thenormal conduct of war, and are not considered to be unfair tricks.Hence, if the war be just, strategems, including ambushes, are notwrong in themselves.

For the safeguarding of the common welfare, it islawful to carry on the acts of a just war, and to wage fights, ifneed be even on Sundays and holy days.