Exterminate the orcs! (or some other cannon fodder monster)

[hamishspence]

All we really want is to get out alive, which comes with no guarantees, and preferably with treasure, because gold's the major source of xp. Every unnecessary fight is a loss of resources that we may need when the GM rolls for wandering monsters later.

I don't know exactly when the kill them all mentality entered D&D, but oddly it doesn't look like its a part of the original game.

Maybe it was "AD&D" that started the trend?