How did fix aid Fogg while in San Francisco?What was the cause of the disturbance?

There was a political demonstration taking place on the streets. As Englishman, they were not well received, and Fix ended up taking a punch that was meant for Fogg.

A big brawny fellow with a red beard, flushed face, and broad shoulders, who seemed to be the chief of the band, raised his clenched fist to strike Mr. Fogg, whom he would have given a crushing blow, had not Fix rushed in and received it in his stead.