Since the main road is blocked with so many vehicles, Henry and his ambulance drivers try to cut across the countryside. The Austrian and German armies have broken through the Italian lines, and a massive retreat from the front begins. Henry returns to Gorizia and is plunged into battle. Before he leaves, Catherine tells him she is pregnant with his child. But Henry eventually has to return to the front. She begins to sneak into his room at night and they conduct a love affair all summer. While Henry is recuperating, Catherine Barkley is transferred to the hospital and when Henry sees her again, he realizes he loves her. Fortunately one doctor, Valentini, is able to remove the shrapnel from Henry's leg. When he arrives, he discovers the hospital is badly managed and the doctors are incompetent.

Henry is taken to an American hospital in Milan for treatment. He is innocently eating macaroni and cheese with the other ambulance drivers when a mortar shell crashes through his bunker, killing a driver and injuring Henry's leg. Soon, Henry goes to the first major battle in which he has taken part. As their flirting deepens in the following days, Henry is able to coax kisses from her, and she asks him to say he loves her before acknowledging that this is only a game. On their first meeting, she tells him the sad story of her fiancé who was killed in the war, whose riding crop she still carries. When Henry returns from leave, his roommate Rinaldi introduces him to two English nurses, Catherine Barkley and Helen Ferguson, and although Rinaldi had been interested in Catherine, the immediate chemistry between her and Henry is obvious. Then the officers go to the officers' brothel for the night. He spends the evening with his fellow officers, who mock the regiment's priest for his celibacy. As the novel opens, Henry is about to take his winter leave. The narrator, Lieutenant Frederic Henry, is an American who has joined the Italian ambulance corps as a volunteer. It is World War I, in 1916, and the Italian army is trying to hold off the united forces of Austria and Germany.

A farewell to arms first edition