Whether a state requires a retreat or not is not the issue. Disengaging and seeking cover and concealment is a sound pragmatic tactic. I will be a good witness as to what I saw as I was heading for cover, which may be nothing more than melting into a "herd". The key here is self-defense and it only works if you are completely in the self defense mode.

If there is a need for you to be involved, and there very definitely can be a need, you are out of the self defense mode and into the "involvement" mode which can be synonymous with "combat" mode if escalation occurs. You are no longer a reacting victim but a party to the fracas.

I am not saying that this might not happen and a moral code may require that I do get involved. But if I do, I can forget the self defense argument, I am now in a participant situation. I don't say don't do it, just that you shouldn't use the term self defense when describing it, at least under Tennessee law.

As others have stated , I could easily find myself reasoning that I should be involved, but I am well aware that, from that point on, I no longer can claim self defense without fear of rebuttal.

Now if there is nowhere to run or hide, the choice is easy, be alert and take note of everything that happens for later relay to LEOs.