Laws of War - Early Sources and History

Early Sources and History

Attempts to define and regulate the conduct of individuals, nations, and other agents in war and to mitigate the worst effects of war have a long history. The earliest known instances are found in the Hebrew Bible (Old Testament). For example, Deuteronomy 20:19-20 limits the amount of acceptable collateral and environmental damage:

When thou shalt besiege a city a long time, in making war against it to take it, thou shalt not destroy the trees thereof by forcing an axe against them: for thou mayest eat of them, and thou shalt not cut them down (for the tree of the field is man's life) to employ them in the siege: Only the trees which thou knowest that they be not trees for meat, thou shalt destroy and cut them down; and thou shalt build bulwarks against the city that maketh war with thee, until it be subdued.

Similarly, Deuteronomy 21:10-14 requires that female captives who were forced to marry the victors of a war could not be sold as slaves.

In the early 7th century, the first Caliph, Abu Bakr, whilst instructing his Muslim army, laid down the following rules concerning warfare:

Stop, O people, that I may give you ten rules for your guidance in the battlefield. Do not commit treachery or deviate from the right path. You must not mutilate dead bodies. Neither kill a child, nor a woman, nor an aged man. Bring no harm to the trees, nor burn them with fire, especially those which are fruitful. Slay not any of the enemy's flock, save for your food. You are likely to pass by people who have devoted their lives to monastic services; leave them alone.

Furthermore, Sura Al-Baqara 2:190-193 of the Koran requires that in combat Muslims are only allowed to strike back in self-defence against those who strike against them, but, on the other hand, once the enemies cease to attack, Muslims are then commanded to stop attacking.

In medieval Europe, the Roman Catholic Church also began promulgating teachings on just war, reflected to some extent in movements such as the Peace and Truce of God. The impulse to restrict the extent of warfare, and especially protect the lives and property of non-combatants continued with Hugo Grotius and his attempts to write laws of war.