How to loosen a dog's jaw lock?

Today a stray dog that roams in my area ( which I’ve befriended )
attacked a smaller dog (yorkshire).
He actually was in the right, but I won’t recount what happened to the poor stray… I’ll just say that humans, when gathered together are mayhem.
I tried to protect the stray, but I couldn’t shoe off the thrashing, discoordinated kicks and the many disorderly attempts to harm the grounded dog…made by about 20 – 25 grown men gathered around it (and me). Not to mention the weight of the guy standing on the dog’s neck…
I couldn’t release the poor stray and nobody was in their right minds enough to listen to what I was shouting ( whilst pushing people away and socking them in the stomach ) : ” You’re making it worse!” ” That’s not the right way!”
during al this I was trying to press the dog’s soft parts under the jaws, the glands… pulling at its tail…
There wasn’t much of the large stray’s body exposed, being covered with human feet and stinking people’s shoes.
As I tried to give him a headlock I had a flying beer botle land on the back of my head.

Anyway…

I know a few techniques which have worked in the past.
I want to avoid one of them, I find it unnecessarily brutal.

What can you suggest?