Catherine Barkley arrives at the hospital, to which she has been transferred. Once again, she and Lieutenant Henry declare their love for each other, after which they have sex in the hospital bed. Henry and Catherine spend the summer together while he recuperates from an operation on his leg, visiting restaurants around Milan in the evening and then spending nights together. At summer's end, however, Lieutenant Henry is ordered back to the front, and Catherine tells him she is three months pregnant. On their last evening together in Milan, Henry buys a pistol, and he and Catherine take a room in a hotel.
Soon after Lieutenant Henry's return to the front, the Austrians (now joined by German troops) bombard the Italian army and eventually break through the lines near the town of Caporetto. Henry and the other ambulance drivers retreat with the rest of the Italian forces in a long, slow-moving column of troops and vehicles. They pick up two Italian engineer-sergeants. Finally, the ambulances pull off the main road. When one of the vehicles becomes stuck in the mud, the two sergeants refuse to assist in the effort to dislodge it and disobey Lieutenant Henry's order to remain with the group. He fires at them, wounding one; another ambulance driver then uses Henry's pistol to finish the job. Henry and the three drivers abandon the ambulances and set out on foot for the Tagliamento River, across which lies safety.
