[benj111]

"The mythologizing of the Samurai, their honor-above-reason mentality"

Agreed, I was focussing more on the not tactically advantageous, rather than ascribing an honour code per se.

It is generally a good idea to agree weapons beforehand, it helps keep the battlefield survivable. The 20th century wasn't known for it's 'honour' but WW2 combatants did refrain from using chemical weapons for example, and nukes were never used in the cold war and it's proxy battles. I'd label that as part of an honour code? I'm not making the case too forcefully though.

[robotresearcher]

More like fear of reprisal than honor. Chemical and nuclear weapons are very hard to defend your civilian population from. Mutual Assured Destruction has worked so far but I wouldn’t call it an honor code.

[benj111]

Germany fought to the end in WW2, the eastern front was particularly brutal. I suspect there were already fears of reprisals.

I wasn't thinking MAD specifically, although I'm aware of at least one example where Russian early warning picked up an incoming object that appeared to them to be a missile, and they didn't respond, which seems very un MAD. I was thinking of the proxy wars, Vietnam, Korea, etc. I'm not even sure the threat of nuclear attack was used. I suppose you could say that's part of MAD (not attacking allies), if that were the case, wouldn't the same reasoning extend to not fighting them in the first place, in the same way there were never any conventional wars between Russia and the US?

So agreed it is mainly about self preservation, but I would say it goes a little further than that.