Short sentences deliver facts, while the longer and more complex sentences provide commentary.
Consider the description of the soldier’s stories. It begins with a short statement.
Even his lies were not sensational at the pool room.
Krebs feels isolated and ignored. His stories don’t get enough attention, so he makes up stories. This one simple statement captures the pain and loneliness he felt.
To further delve into why Krebs is ignored, we are provided directly next with a sentence that is so complicated it’s hard to believe it was written by the same hand.
His acquaintances, who had heard detailed accounts of German women found chained to machine-guns in the Argonne forest and who could not comprehend, or were barred by their patriotism from interest in, any German machine-gunners who were not chained, were not thrilled by his stories.
This compound-complex sentence highlights the confusion and difficulty of the situation. The townspeople are used to hearing horror stories. Another horror story, no matter how fantastic, just can’t compete.
As the reader feels the sharpness of the short sentences, there follows the meandering quagmire of the second sentence.
Just as he is trying to wind himself into popularity, the sentence winds to get the reader’s attention. We feel sorry for the old soldier, because even his lies are not interesting.
In the opening paragraph of Hemingway's 1925 story, two sentences that describe a wartime picture of Krebs with another corporal and two girls set the tone and style:
"The German girls are not beautiful. The Rhine does not show in the picture."
These simple, declarative sentences communicate the disillusionment reflected in post WWI literature of the "lost generation" authors when they reflect on what the war meant. There is nothing heroic or romantic about Krebs's European service; the girls are ordinary-looking, and the landscape is not picture-postcard worthy. The sentences are blunt and informative, just like what they describe. Hemingway's narrative style is intentionally journalistic, and he once described it as "the iceberg theory," implying that great meaning is found beneath the surface of what is obviously visible.
Further into the story, Hemingway does employ other sentence structures, such as:
"Krebs acquired the nausea in regard to experience that is the result of untruth or exaggeration, and when he occasionally met another man who had really been a soldier and they talked a few minutes in the dressing room at a dance he fell into the easy pose of the old soldier among other soldiers: that he had been badly, sickeningly frightened all the time."
This compound-complex sentence (by definition, at least two independent clauses and at least one subordinate clause) conveys the complexity of Kreb's internal life. It is a lengthy sentence full of emotional outpouring. He is uncomfortable with the exaggerations soldiers sometimes use to help civilians understand what it is like to experience war and experiences relief when he meets a veteran with whom he can share a few minutes of honest conversation. The dependent clause at the end of the sentence is a fragment—the shortest part of this sentence—but also the most revealing of Krebs's psychological state: an admission of fear, the antithesis of what society at this time was ready to hear from soldiers returning from WWI.