He was both onlooker and participant.

His long months of culture and refinement shuddered at the sight; then the present was blotted out of his consciousness and the ghosts of the past possessed him, and he was Martin Eden, just returned from sea and fighting Cheese-Face on the Eighth Street Bridge.

He suffered and toiled and sweated and bled, and exulted when his naked knuckles smashed home.
They were twin whirlwinds of hatred, revolving about each other monstrously.

The time passed, and the two hostile gangs became very quiet.

They had never witnessed such intensity of ferocity, and they were awed by it.