But you may destroy the trees that you know do not produce fruit. Use them to build siege works against the city that is waging war against you, until it falls.
They are here directed what method to take in dealing with the cities (these only are mentioned, Deu 20:10, but doubtless the armies in the field, and the nations they had occasion to deal with, are likewise intended) upon which they made war.
Commenting on Deuteronomy 20:10-20
Only the trees which thou knowest that they be not trees for meat,.... Which might be known not only by their not having fruit upon them, but by other tokens, and even at a time of year when there was no fruit on any, which might be sometimes the season of a siege: thou shalt destroy and cut them down; if so to do was...
thou shalt build bulwarks against the city that maketh war with thee--It is evident that some sort of military engines were intended; and accordingly we know, that in Egypt, where the Israelites learned their military tactics, the method of conducting a siege was by throwing up banks, and making advances with movable towers, or with the testudo [WILKINSON]. Next: Deuteronomy Chapter 21