Hemingway's novel A Farewell to Arms offers one of the most accurate depictions of war in literature. In chapters 3 and 4 more particularly, we note a number of elements related to the theme of war that, besides, is the main one in the novel together with love. In these chapters, the place given to war has growing importance, and it has an almost palpable presence, however distant it may feel. Hemingway's writing suggests that Henry and his entourage are outsiders to the war, and he uses Nature as a mirror for the situation of warfare at the front, introducing the reader to the idea of “false soldiering”, and loss of a sense of purpose. 
In these chapters it is confirmed that Henry is an outsider to war notably with numerous descriptions, starting with portraits of his weapons. As a matter of fact, his Austrian rifle and his war weapons are described as decoration items. He calls them “picturesque” but develops a weird sense of admiration for these items. We can say that he thinks of his weapons as beautiful for their aesthetic and does not see their real meaning consequently indicating his outsider position. Moreover, the fact that the equipment is described as "lovely" or "shiny" stands in stark contrast with usual depictions, as we may think that they should be dirty, and covered in mud. This indicates that they are not used, and once again they are reduced to decorating the room, a proof of Henry's distance from the war and of the fact that he is not directly affected by it. Moreover, we can say that this can be foretelling of Frederick’s realization about his rifle; he will eventually realize that they are instruments of war and death. 
When describing the sound of war at the beginning of chapter 4, the narrator uses the word "nuisance" which is definitely not the word that would first come to one's mind for such description. As a matter of fact, one may expect adjectives such as “horrifying” or “hammering” to describe war’s noise. We can state that he is talking about the war with an understatement with only consequence to make his “pajamas flap”. In the same way, a fully committed soldier should be up and about before the firing begins.
The “brown” mountains, described in the beginning of chapter 3 create an idea of distance as the war is happening there, creating opposition to Nature. This also is the last apparent consequence of death and war on Nature and creates a sense of distance of the war as the mountains are far away from the narrator. 
Nature is indeed a very important theme in these chapters as it influences the whole mood of the chapters and mirrors the situation.
Spring is here associated to joy and revival “it was a lovely spring morning”; the endless rain is gone and now replaced by sun and happiness: the snow has melted. This also is surprising as the primary sense of death of the book seems to have disappeared in those lines. But there is a sense of build up, the snow has left and “more guns” have arrived, death is coming but they do not know when “there will be an offensive”.
This war seems to be an antithesis to other types of war as it is described as “picturesque” and “beautiful” even if “more guns” are here. One should bear in mind that the latter two adjectives are first used by Catherine and might reflect her impression that compared to what happened to her fiancé in France, this is indeed so unusually quiet and harmless that it may seem “picturesque” and “beautiful”.
Everything is clean, green and calm, too calm. This gives the reader the feeling of calm before a storm, or in this case, before a battle. “The fields were green and there were small green shoots on the vines [...] green on their slopes” and “the war starts again next week”, we could accordingly say that Hemingway is describing nature as picturesque and beautiful, thus not connecting it to war. This is another antithesis as green is associated to nature, hope and life but also to sickness and failure.
Frederick seems to unconsciously sense a war/battle coming, indeed he says “There was the beginning of a feeling of dryness in the nose that meant [it] could be hot later on” as if he foreshadowed what is going to happen as the plot develops. We could also add that it seems like nature itself is giving him a sign that there will be war again, this relayed when Rinaldi says “the war starts again next week”.
“False soldiering” plays a very important role in Hemingway’s portrait of war. Revealed by his discussion with Miss Barkley, and Frederick's feelings about his leave, it gives a realistic view on people's mentality during wartime.
In chapter 4, Frederick meets Catherine Barkley in a garden while his friend Rinaldi sits to talk with Nurse Ferguson. Catherine talks about her dead fiancé whom she lost in the battle of the Somme. While talking about him she states that she thought he would come back with a few “sabre cuts” and “few injuries” but then says that he was “blown to bits”. Hence the mentality of many people of the time who thought that war was just like in the movies and had a romantic, patriotic and highly "picturesque" vision of war, conversely confronted to its morbid reality when she says “That's the end of it”. This can also be a foreshadowing when Henry will be wounded, transported to the hospital and taken care of by Miss Barkley. We could add that she seems to think everything is a “silly” joke as she mentions this word more in a lot of her dialogue.
In addition, Miss Barkley makes comments that are as ambiguous as interesting. In some cases, she even seems to have a better understanding of war than Henry himself, like when she states that "people can't realize what France is like", "He didn't have a sabre cut. They blew him all to bits", two quotes that translate her disillusion about the war after her fiancé’s death, and explain her pessimistic view on the continuing of the war : "we'll crack". On the other hand, she gives the impression that she isn't very well informed on the war, and as Henry states later on in the novel, she sounds a little crazy : “I've heard about it", "This is close to the front isn't it ?", "It's a silly front", "are they going to have an offensive ?", "I remember having a silly idea". This somehow discredits her pertinent remarks and leaves us wondering whether she really knows what she is talking about or only repeating what she has heard from others.
Rinaldi seems to indicate that false soldiering is a very important part of the army as he says “self inflicted wounds [...] a few real wounded” thus indicating that most soldiers are, as Frederick, not interested in the war and prefer to wound themselves to avoid it. There again, is a loss of the sense of purpose in the army. This is also linked to our first part, as it shows that the effects of war on the characters are still indirect, hence their inability to identify with it. Lastly, this passage could be seen as a foretelling as Henry will later desert the army, just like the men with self-inflicted wounds want to.
Throughout the novel, the characters constantly try to distract themselves from the war, and to escape its omnipresence, however distant it might be. This is why Rinaldi pretends to love every woman he meets. It is also what Henry is willing to do during his leave, thinking about anything but the war : he goes in bars and cafes and sleeps with a different woman every night : "I had gone to no such place [...]and not caring". But it doesn’t help him, or at least, not for very long and he is quickly bored and almost disgusted by the way he spent his leave. This, indeed, is clear when he talks to the priest and comes to the realization that he has wasted his precious time away from the front for nonsense. He hasn’t done what he has planned to do, that is to say visit the Abbruzzi, and he hasn’t had a great time either: "I myself felt as badly as he did". His drunken guilt expressed in a full paragraph of free indirect speech emphasizes his loss of a sense of purpose when far from the front: "I explained, wine-fully, how we did not do the things we wanted to do, we never did such things". Ironically, what was supposed to make him forget the front will eventually only make him miss it (Teacher’s question: Does he wish he had stayed in Gorizia or that he had gone to the “clean, cold and dry” Abruzzi? I choose the second option.) As a matter of fact, war fills Henry’s mind, and afflicts him like a headache, painful and most importantly chronic. 
Despite Frederick missing the front, his return to Gorizia is purposeless.
When he comes back to the front, the realization that he is replaceable and that he isn't vital for the functioning of their small base strikes him rather violently, and seems to profoundly hurt him, even though he doesn't show it very much. He states: "I had imagined that the conditions of the car [...] Evidently, it did not matter whether I was here of not". Considering that his leave was not successful, and he would rather talk about the war front than telling others about this leave, coming back to the front, where he thought he would be at ease and seeing that he wasn't needed, must have shaken his convictions, that is if he had any. It must have reinforced his loss of a sense of purpose as well as his feeling of being an outsider, already strong because of him being an American in the Italian army. Indeed, he answers that “there is not an answer for everything” when Catherine Barkley asks him why he is a foreigner in the Italian army. Again, we can state that this chapter foreshadows when Frederick will desert from the Italian Army as he will realize that he does not belong there, and that it might actually get him killed. 
The quote “the whole thing seemed to work better while I was way” shows, again, that he does not care about his leave but considers it as a distraction and he appears to prefer war which is why he regrets (Again, I tend to disagree, there is no conclusive sign of regret as to his uselessness, it doesn’t seem to bother him) that things work better without him. We could also add that when Rinaldi says “You talk like a time-table” he seems to indicate that Frederick speaks with no further description about his leave and just gives the facts. Lastly, his loss of a sense of purpose is shown by his many uncertainties. He does not know whether to go and report or clean up; he does not have an alarm clock thus not having a work day and doesn’t have a purpose and does not understand war. He does not know why he didn’t go to the Abruzzi ; he went to Milan, Firenze, Napoli… but did not enjoy it, he seems to feel drained and useless “It was all I had left it except that it was now spring”. In conclusion we could say that the narrator feels purposeless when it comes to his life.
As a conclusion, the distance of war from the main character does not prevent him from being completely absorbed by thoughts about the front. Even during his leave, he comes to miss being there (Again, I would say he blames himself for not going to the Abruzzi mountains and their purity, not for taking his leave). His return to a well functioning and "beautiful" front strengthens his feeling of worthlessness and leaves him even more purposeless. Ironically, he wants to participate in the war effort but he has no purpose and is an outsider to the war. As war doesn't affect him, he can't seem to identify with it. The chapters happen during a period of calm as war has stopped during winter, but instead, it creates a buildup of tension, reminding us that war is close, hidden amid the greenery of the landscape. 

Pierre, Elisa, Céleste, Charlotte and Ralu