I’m just a bar bouncer with some jiu jitsu training, but like our hulking friend above hinted at, multiple attackers is BAD NEWS. I’ve dealt with one such situation professionally and it was very, very ugly, with the guy I was doing my best to protect going to the hospital with serious injuries inflicted by a group of 5 coked-up bikers. A guy my age (38) was recently beaten to death in my town in a multiple attacker scenario. No amount of jiu jitsu or karate is going to stop a brick to the head coming from your seventh or eighth simultaneous attacker. The poor guy held on for a day before he died. Sadly, stuff like this can happen.
I would be very, VERY skeptical of any hand-to-hand martial art that claims to give you any real chance fighting off multiple attackers. I don’t know of any that actually work in real life. The instructors selling the notion that they can prepare you to fight off several attackers at once are pure snake oil salesmen if you ask me.
The best martial art for fighting off a surprise 5 on 1 scenario is, in my opinion, combat handgunnery. Know all of your applicable laws in your jurisdiction, but in my area a multiple attacker scenario constitutes disparity of force, justifying the use of lethal force in defense of your self or those under the mantle of your protection (i.e. daughters).
The best overall defense is to not be a target. I assist my BJJ instructor in delivering self-defense training to our area’s home care hospice workers. We’re not teaching people to choke out grandma here, we’re teaching grip-stripping techniques for when grandpa gets grabby and, most importantly, we teach tactics for awareness and safety in unfamiliar locations. Always backing into your parking space. Walking confidently, posture up and head on a swivel, scanning your surroundings and avoiding areas where you feel there might be trouble. Open your car door and do a complete 360 scan of your area before you get in. Think about your safety at all times sort of stuff.
Jiu jitsu is great for self-defense. Learning how to escape when someone’s holding you down is very valuable and very effective. Learning how to fall is probably the best self-defense skill you’ll pick up from BJJ. Most of us are in much greater danger from falling than we are from aggressive hoodlums.
Good luck and stay safe!