Chapotraphouse

It is probably one of the biggest overarching messages of the work that honor is for people who want to die, and a good general does not want his army to die, in contrast to the traditional warrior culture ethos where such a thing is noble. He does talk about other things, but the main subject if overwhelmingly how to approach warfare pragmatically (including by not going to war in the first place).

The only thing that stood out to me when I read it as a kid was never back your enemy into a corner with no escape, because they will fight viciously knowing they're fighting for their only chance. Always make sure there's a way for them to escape so that either they fight a retreating action or they break and the soldiers abandon formation. I took that to heart, I have never once backed an enemy army into a corner they can't escape from.

I know there must be some actual technical strateg-er-y in there

For the most part, not really. It's a whole lot of pretty basic common sense stuff like "know what you can do and what you're facing", "don't abuse your own soldiers so they hate you because you quite literally need them to be willing to die on your behalf and stand by you even in the direst situations", "don't just assume shit will go your way, make sure it does", and "pack a lunch dipshit, logistics is actually important", so it is quite literally a basic guide for elite failsons on not completely fucking up at every opportunity.

It reminds me a lot of how The Prince has a whole lot of "look, ok, just like go camping and hunting instead of trying to rule, because you're not good at that and should just hire some experts to do it for you while you go play pretend soldier in the woods, ok?" stuff in it, alongside encouragement for nobles to be as brutal as possible towards one another while immediately giving any stolen wealth gained from that to the public and generally leaving the common folk alone.

It is literally Not Fucking Up The War Immediately For Dummies.