Bill was watching a prize fight in Vienna and when the black fighter knocked out the white one and tried to make some kind of statement, the white guy went after him again and eventually there was such a ruckus that the black guy had to run for his life.
Bill remembers this so well because he is very interested in and perturbed by the prejudice made so obvious in his travels. He differentiates to a certain extent which places he likes more based on the way that people treat each other in them. For this reason he tends to say that he likes Paris more than Vienna, he feels they are less prejudiced, perhaps more civilized.
In Chapter 8, Bill Gorton speaks with Jake and recalls visiting a prize fight in Vienna in which a black boxer, who he describes as "noble-looking," knocks down a local fighter and is pelted with objects from the crowd. The fighter tries to protect himself with his glove and to make a speech in his defense. When a white man hits the boxer, he knocks the man down. The crowd then begins to throw chairs, and Bill goes home with the boxer, who doesn't have his clothes. Bill loans the man clothes and tries to collect the boxer's prize money, but the fight promoters refuse to pay him, as they claim he caused the ruin of their hall. The promoter states that the black boxer was supposed to let the local white boxer win, but the white boxer couldn't even stand after trying to punch the black boxer. In the end, the black boxer gets his clothes back (minus his watch) but no money. Bill lends the boxer money to get to Cologne, where the boxer lives.
Bill remembers this vividly because the injustice of the situation chafes at him. Brett says that Vienna is much like Paris at the moment, and Bill agrees with her. They both feel negatively about the idea that Paris is affected with the same sense of immorality that Bill witnessed in Vienna. Soon, Jake and Bill will head to Spain for fishing to get away from the sense of immorality and degradation that they see in Vienna and Paris.