What does Casy tell Tom about the labor strike? What caused it?

While continuing on his walk, Tom finds Casy, who has been released from jail. He is with a group of men that are on strike. Casy claims that people who strive for justice always face opposition, citing Lincoln and Washington, as well as the martyrs of the French Revolution. Casy, Tom and the rest of the strikers are confronted by the police. A short, heavy man with a white pick handle swings it at Casy, hitting him in the head. Tom fights with the man, and eventually wrenches the club from him and strikes him with it, killing him.