The Preservation of Trees (Deuteronomy 20:19-20).
Analysis using the words of Moses:
a When you shall besiege a city a long time, in making war against it to take it, you shall not destroy its trees by wielding an axe against them
b For you may eat of them, and you shall not cut them down, for is the tree of the field man, that it should be besieged by you?
b Only the trees of which you know that they are not trees for food, you shall destroy and cut them down
a And you shall build siegeworks against the city that makes war with you, until it fall.
Note that in ‘a' the siege is a long one but in making war against them they must not cut down the trees as a matter of policy, while in the parallel they can be used to build siege works while the siege is still in progress. In ‘b' they must especially not cut down the trees from which they can eat, while in the parallel they may destroy and cut down the trees which are not trees that produce food if necessary.
‘ When you shall besiege a city a long time, in making war against it to take it, you shall not destroy its trees by wielding an axe against them, for you may eat of them, and you shall not cut them down, for is the tree of the field man, that it should be besieged by you?'
An important principle was now being laid down, the preservation of trees in warfare. One of the worst crimes of the later Assyrians and Babylonians, shared also by the Egyptians, was their destruction of trees (Isaiah 37:24; Isaiah 14:8). But however long Israel were besieging a city they must not cut down the fruit trees. Indeed they might well need to eat from them. And they should consider that the trees are not men. Trees would not fight them or stab them in the back. They were there simply for man's benefit. Again there is the stress on mercy wherever possible.
‘ Only the trees of which you know that they are not trees for food, you shall destroy and cut them down, and you shall build siegeworks against the city that makes war with you, until it fall.'
The only trees that they should cut down were those which were not fruit trees and which were needed for siegeworks. It was permitted to cut these down for the purposes of building siege weapons, including ladders for scaling walls and protective defences behind which they could find shelter.