An oily, manipulative orator who rouses the workers to rebel and unionize against Mr. Bounderby, Slackbridge is also responsible for Stephen's alienation from all the other factory workers when Stephen refuses to join the union because of a promise he made to Rachael. Though on the side of the workers, Slackbridge is not much of a better man than Bounderby.
The timeline below shows where the character Slackbridge appears in Hard Times. The colored dots and icons indicate which themes are associated with that appearance.
Book 2, Chapter 4
...working conditions. They meet in a hall somewhere in the town, where a speaker named Slackbridge incites their rage against the cruelty of the industrial system and insists they must form... (full context)
Book 3, Chapter 4