It's funny that you mention this because one of my fav fight scenes in any movie is at the beginning of Hero, the 2002 movie with Jet Li. When Jet Li and Donnie Yen's characters face off at the beginning of the movie, they imagine the fight in their heads, with a shift to black&white noting the shift to an imagined fight. Their "simulation" leads to both sides recognizing that Jet Li would win, and Jet Li finishes his opponent off with one swift movement. The scene actually takes place at a chess courtyard, with an old man playing music as they "fight".
Of course! "All is fair in love and war", as the saying goes. Stabbing in the back is a tried and true method of winning a conflict.
Rules of war hold up only in certain cases, like:
1. You're so much stronger than your opponent that you can unilaterally uphold rules that disadvantage you in combat.
Example: USA in Iraq and Afghanistan.
2. Both sides expect to survive the fighting and possibly engage again in the future, so it makes sense for both sides to play by the rulebook to reduce costs of ongoing conflict.
Example: not shooting at enemy medical transports, and not using yours for combat operations, lest the enemy starts shooting your medics. Extreme example: MAD doctrine - nuclear powers are bound by the ultimate rulebook, breaking which will annihilate them all. That's what kept USA and USSR from engaging in full-scale warfare. That's what keeping China, Russia and USA from direct confrontation today.
3. There are powerful third parties willing to intervene against the side that breaks the rules.
Example: Geneva Conventions, to some extent (I don't think anyone got actually pounded over breaking them). Also sports.
No high-minded rule can overcome the fear of death. So, for a warring party to hold themselves to a standard, the stakes either have to be so low that they can do it out of virtue (or PR considerations), or breaking the rules must be more dangerous than upholding them.
