Somewhere in this forum the developers mentioned when you return to combat, you are not doing so as a wounded (same) soldier, but as another (new/different) soldier just entering combat. This makes more sense to me than restarting at a field hospital tent. I'm not completely against it, but the hospital tent would suggest you were evacuated off the field of battle, fixed up, then returned to combat. I don't believe that's very realistic for the time period.