Deuteronomy 20:16

Cp. Deuteronomy 7:1.

19, 20. Fruit-trees are not to be used for bulwarks and battering rams. The words at the end of Deuteronomy 20:19 should probably be read as in RV, 'for is the tree of the field man, that it should be besieged of thee?' i.e. the tree does no harm and is not to be treated as an enemy. Wanton destruction is not permissible even in war.

All these rules were designed to mitigate as far as possible the evils of war. There is to be no destruction of human life and property beyond what is actually necessary. The conduct of war is to be guided with reason and mercy.