What is the main conflict in Interesting Times by Terry Pratchett?

Lord Hong is chief antagonist in the novel. He sets up Rincewind and the Red Army to take the blame for the Emperor's death so that he can become the new ruler. Lord Hong represents everything that is wrong with the Empire. He is willing to sacrifice the peasants of Hunghung in order to win the Emperor's throne and believes they should be willing to die at his bidding. The Empire only dissolves completely when Lord Hong is killed.