A couple of quotes from The Untouchables:
Malone: You wanna know how you do it? Here’s how, they pull a knife, you pull a gun. He sends one of yours to the hospital, you send one of his to the morgue. That’s the Chicago way, and that’s how you get Capone! Now do you want to do that? Are you ready to do that?
Capone: When you got an all-out prizefight, you wait until the fight is over, one guy is left standing. ‘N’ that’s how you know who won.
If I wasn’t so tired I might spend a few minutes discussing how these quotes relate to real life. Ok, maybe I’ll try.
IMO, if you go to war you go with the intention to completely overwhelm the enemy. As Sean Connery’s character illustrates you hit them so hard they cannot conceive of lifting their head up out of the mud. There is no reason to use bombs and bullets unless you wish to kill and if that is your task then you let them wonder if they didn’t start a fight with the devil.
Now if we go with Capone’s commentary we can take two different perspectives. The first is the literal interpretation. Last man standing is the victor.
OTOH, we can argue that it does not have to be taken literally and that a better measure can be assessed after some time has passed. Does the last man standing walk away or do they just collapse from exhaustion. It is something to consider.