Several NCR trooper are scattered throughout the no-man's-land between Nelson and Camp Forlorn Hope. Most of them are missing several, if not all, of their limbs. Caesar's Legionaries have placed armed frag mines near or under their bodies. (The soldiers in Forlorn Hope will occasionally give a warning about the Legion practice of placing traps on or near the dead and injured.)
When you get close to one, they will warn you to stay away or ask you to kill them. It is impossible to rescue any of these soldiers alive. If you are able to disarm the mine there is no way to interact with the injured trooper to heal them and there are no non-player characters in Forlorn Hope to tell that the traps have been disarmed. The only way to help them is to end their suffering by killing them. No Karma or reputation is lost (or gained) for killing them.