That is utilitarianism. In Farewell to arms, Hemmingway's main Character is in Solferino and an explosion happens in the middle of a convo in a large foxhole and he is the only one left alive. Nobody jumped on a grenade there. But then there was a movie called TOP SECRET where one of the bat mans the Val Kilmer dude whom people say I look like, well, he jumps on a grenade to save everyone in the room and then everyone else gets blown up. So that was like a reverse Hemmingway.

Utilitarianism is doing something that helps more people in the end. Sacrifice is a human concept, I doubt there are animals who would act like this.

Although humans in the past have sacrificed animals to make them learn a lesson. Since they don't sacrifice themselves.

And anyways the only way to be human, the only way to live is to take chances, and if you are going to be inhibited and worried about what would go wrong if I did this, would someone else die if I saved 5 others, then you are a loser.

When peace is broken and there is a situation you have to think fast and do something quickly. Peace must be maintained, even the law realizes that in certain situations when there is an act of god, humans have to counter act these disasterous situations by acting executively and making a firm judegment at the time to save the day, and if you make a mistake, well, it may not have been the right thing to do, but we are human and are alotted mistakes. The law looks away from heros that fail.