All's Fair in Love and War?

I have never understood all the rules of engagement in war, the international law regarding it, Queensbury rules,Geneva Convention,International courts and suchlike. War is about the breakdown of relations between countries and ergo one would suppose all rules governing their respective behaviour so it is a fiction that such observances can have any traction in the real world beyond liberal la la land.If they could there would be no war in the first place.

To hobble one's own side with ridiculous injunctions is to risk defeat on the battlefield and countries that do that to their soldiery are decadent and doomed to destruction.Israel and its prosecution and imprisonment of the soldier who shot a prone Palestinian is a case in point. The brute had already attacked Israelis with a knife and the soldier did nothing wrong in taking him out and should have been given a medal for services to humanity not hauled before a court and sent to jail. But when it comes to Israel normal rules of justice and fairness do not seem to apply and it is deemed guilty before the court of international opinion merely for existing.In reaching such a perverse judgement it has done serious harm to itself and cause and suggests a country regrettably  unsure of its inalienable right to defend its interests and very existence.