Henry returns to Gorizia. The major fills him in on the summer full of combat, and comments that Henry was lucky to have gotten wounded just when he did. The major adds that if he had gotten an injury he probably wouldn't have returned to the front.
Henry was able to escape the war for the summer, but now reality has asserted itself. Even the major has lost faith in the war, and would desert if given a chance.
Henry then reunites with Rinaldi. Due to all the casualties from the summer of fighting, Rinaldi has had plenty of experience operating on wounded soldiers, and now drinks and womanizes more heavily than ever. Rinaldi notes that Henry seems like a "married man," then asks whether Catherine is good in bed. Henry refuses to tell him. Rinaldi notes with surprise that this seems to be a "sacred" topic.
As the war has intensified, Rinaldi's drinking and womanizing seems less macho and more a desperate ploy to forget the war. Rinaldi's "sacred" crack highlights that Henry has made the sort of religious commitment in his love for Catherine that the priest predicted in Chapter 11.
At dinner, the mess hall is quiet, as there are fewer men at the table. Rinaldi, getting drunk, tries to bait the priest as he used to. But his jokes fall flat, and he gets angry at the priest and the war and announces that he may have syphilis before heading off to the whorehouse.
Through what begins as joking, Rinaldi reveals a deep desperation and anger that God could let horrible things happen in war. Rinaldi's attempts to forget the war by womanizing may have given him syphilis. In other words, you can only hide from reality for so long.