Henry and Catherine say their goodbyes in front of the train station in the rain.
Rain is always a bad omen in the novel.
The train is crowded, with every seat taken. When Henry gets on and takes the seat that he had paid someone to hold for him, an Italian army captain takes exception. After some back and forth, Henry lets the captain have the seat and goes to sleep on the floor.
The episode with the captain is a reminder of the petty bureaucratic idiocies that are a part of army life and which take precedence over goodness and fairness.