It is two days before the scheduled offensive and the narrator is sitting in an ambulance waiting for the wounded men's paperwork to be processed. He notices that a limping straggler from a passing column of soldiers sits down by the side of the road. After a brief exchange with the man he learns that the man has a rupture (a non-war-related injury) and has purposefully lost his support truss so as not to have to go back to the front. He lets the man into the ambulance. The man tries to convince the narrator to take him to a hospital but the narrator observes that without paperwork it would do him no good. He tells the soldier, who speaks English and has spent time in the United States, that he will let him out away from his column and then the man should get a bump on the head so that when the narrator returns in the ambulance he can take him to the hospital as wounded. The soldier agrees but when the narrator returns he sees that the soldier, with a fresh wound on his head, is being picked up by members of his regiment.
He returns to the villa at five o'clock in the evening and sends some pre-printed postcards to the United States where he knows they will seem foreign and strange to his relatives. While he is filling out reports he muses on the disposition of the Italian army, his desire to visit Austria after the war, and the chance that France will capitulate to Germany. He fantasizes about taking Catherine Barkley to a hotel in Milan and making love with her. He describes that evening's mess as dull. After some conversation with the priest and some jokes with the other officers, he begins a half-hearted drinking contest [during the course of which we learn that his first name is Frederic though it is rendered in the Italian "Frederico"]. He cuts it short when he remembers that he wants to visit Catherine. Rinaldi makes him chew some coffee beans to keep from being too drunk. At the British hospital, Miss Ferguson tells him that Catherine is not feeling well and advises him to return the following day. He remarks that, though he had taken it lightly, not seeing Catherine now makes him feel empty and lonely.
The following afternoon word goes out that there will be an attack up the river that night that will require all four ambulances. Frederick stops by the British hospital before he leaves and Catherine gives him a St. Anthony medallion to wear around his neck but he puts it in his pocket instead. When he returns to the ambulance the driver tells him that he must wear it around his neck to be protected, so he moves it. They race ahead and catch up with the other ambulances. Frederick remarks on the disposition of a mule train and the beauty of the landscape, particularly the Austrian mountains, which rise ever higher against one another in the distance. It is dusk when they reach the main road that runs along the river.
The ambulances arrive at the ruined rail station by the river where the attack is to begin. Frederic notices a corn stalk canopy meant to prevent the ambulances from being shelled as they evacuate the wounded. A soldier shows him a dugout where his men can wait. Frederic finds the major in charge of the operation and they drink rum. He learns that the attack is to begin after dark. He returns to his men and gives them each a pack of loosely packed cigarettes. They complain of hunger and he inquires at the command post about food and learns that they will be fed as soon as the field kitchen is up and running. He returns to his men and notes that as mechanics they all hated the war. They talk of a recent mutiny by Italian troops who would not attack and every tenth man was shot. They note that the families of men who are accused of cowardice suffer as well, otherwise no one would attack. They argue over the best way to end the war. Frederic insists that the only way to end the war is to win but his men, whom he allows to talk freely, insist it would be better simply to give up and then the war would end. Passini points to the Austrian mountains and states that there is no way to take all of Austria and the others, Gavuzzi, Manera and Gordini seem to agree. Grodini, the quietest of the four, accompanies Frederic to the major's tent where they beg for some cold pasta and cheese. Outside, the bombardment begins. On the way back to the dugout, they narrowly escape being killed by a falling shell.
Frederic and the mechanics eat the macoroni and cheese with their hands and wash it down with wine while the shelling continues. A direct hit on the dugout causes complete havoc and Frederic becomes aware that he is wounded and cannot reach Passini who has lost one leg and is bleeding from the other. He drags himself to Passini and tries to fashion a tourniquet but the man dies. Frederic's head explodes with pain and he feels that his knee has moved to his shin. Pain overcomes him as Manera and Gavuzzi carry him to the aid station. They drop him twice on the way and he swears at them.
While he is waiting for treatment at the aid station, a British ambulance driver offers him a cigarette and Frederic offers him the use of his ambulances. The English driver promises to be careful with them and return them safely to the villa. The English driver, against Frederic's wishes, convinces the Italian doctors to treat him ahead of the others and tells them that Frederic is alternately the legitimate son of President Wilson and the only son of the American ambassador. The surgeon examines Frederic's wounds to the right knee and foot and head and offers him a drink of brandy. The surgeon tells him that the real pain will arrive soon but that he will be well in time. Frederic is loaded into a British ambulance below a wounded man whose blood drips onto him during the journey. The man dies and is replaced by another wounded man at the top of the hill.
Some time passes. Frederic is in a ward at the field hospital. His orderly tries to keep the flies away and it is very hot. He describes the ward and how each morning three nurses and a doctor make the rounds. One morning his orderly is scratching the soles of his feet for him when Rinaldi pays him a visit. Rinaldi is very excited and comical. As in other conversations, he affectionately refers to Frederic as "baby". He brings a bottle of cognac and news that Frederick is to be decorated and even receive a silver medal if he can prove he was heroic. When Frederic replies that he was "blown up while we were eating cheese" Rinaldi insists there was heroism in his actions. Frederick learns that the attack was successful. Rinaldi proceeds to send the orderly for a corkscrew, brag about his increasing skill as a surgeon, suggest that Frederick might also qualify for an English medal and serve the cognac - all the while fawning over Frederic's wounds. He complains that the girls at the bordello have not changed in two weeks and they've become friends. He remarks that the priest is coming with big preparations and then jokes that Frederic and the priest are "a little bit that way"" [meaning homosexual]. He insists that Frederic is an Italian and that they are brothers. Rinaldi promises to send Catherine to see Frederick and makes a rude joke about the difference between intercourse with a good girl and a woman. He departs after lavishing more sardonic affection and leaves the cognac under the bed.
In the evening the priest comes for a visit. He is timid and awkward and seems very tired. He brings English newspapers and a bottle of vermouth. Frederick insists that they drink some of the vermouth and as they drink the priest talks of the difference between the officers and the enlisted men and the differences between those who make a war and those, like Passisni, who would not make war. Eventually their talk turns to the nature of love and the priest, who loves God, makes the observation that love makes one want to serve another. The priest insists that one day Frederic will know this kind of love. The priest leaves and Frederic muses on the sylvan beauty of the priest's rural home in Abruzzi before falling asleep.
After some time in the ward, Frederick is told that he will be sent to Milan in order to get better x-rays of his leg and where he can do therapy after the operation. The night before Frederic is scheduled to leave, Rinaldi and the major from the mess come to tell him he will be sent to the new American hospital in Milan. The major and Rinaldi ask if the United States will declare war on Austria since it has recently declared war on Germany and Frederic enthusiastically and somewhat drunkenly asserts that it will. As they get more drunk, Frederic describes the process of receiving money from his grandfather through sight drafts at the bank. Rinaldi and the major assure Frederic that he will have a fine time in Milan. Before they leave, the major tells Frederick that Miss Barkley is to be transferred to the American hospital in Milan as well.
It takes forty-eight miserable hot hours on the train to reach Milan. During a stop in Mestre, Frederic sends a boy to get him a bottle of grappa. He and his fellow passengers get drunk. Somewhere past Vicenza he asks a soldier for some water and also receives a pulpy orange that he eats immediately.
These chapters give some intimation of Frederic's progress toward realizing the type of love described by the priest, that of wanting to serve someone or something. Frederic admits to himself that when he stays too long drinking at the mess and then discovers that he may not see Catherine, it affects him more than he would have suspected. At this point, however, the war intrudes. Frederic is wounded suddenly by a falling shell while he and his men are eating. The injuries he incurs are severe enough to warrant medals but not so bad that Rinaldi and the major can't express happiness for his return to Milan where they believe he will have a good time while recovering. The knowledge that Catherine will be there as well, sets the stage for a different experience than when he last visited the city and stayed out late drinking and went home with a different girl every night. Significantly, the injuries that Frederic has sustained are the kind that Catherine had originally hoped would befall her fiance. The stage is set for their romance to begin.