about him. They are already caught up in his story, and they want to know what will happen next.

But Bierce doesn't continue the story just yet. The second part of the tale flashes back to formally introduce readers to Peyton Farquhar and to show how he ended up standing on the bridge. He said too much to a federal scout, and he was caught in a plan of sabotage. This little sequence provides necessary background information but also heightens the suspense of the story. Now that readers know about Peyton Farquhar, they are even more interested in what happens to him and they understand better why he is on the verge of being hanged.

The next section returns to the present as Peyton Farquhar falls down from the bridge and loses consciousness. Readers follow with interest as Farquhar seems to escape, swimming away under a hail of gunfire and returning home. But just as Farquhar is ready to run into his wife's arms, he feels a blow to the back of his neck and sees a white light. Then the scene shifts back to reveal Peyton Farquhar hanging dead from the Owl Creek bridge.

This narrative structure, which breaks chronology and seems to blend the real with the imagined and desired visions of a dying man, is effective for enhancing the story's drama. Had Bierce chosen a straight chronological approach, readers would have missed out on the buildup of tension that the first scene and the flashback provide. His chosen structure packs a much more dramatic punch and leaves the reader almost gasping for breath by the end of the tale, which is a surprise for most on their first read. Indeed, Bierce is a master of suspense, and his narrative choices contribute to his success in that area.

Bierce shifts his narration throughout the story as well as presenting the story out of order.  His narration shifts from a conventional third person point of view to a more revealing third person point of view in the second section.  We learn more about Farquar's feelings and his perceptions as well.  The third section then turns into a first person point of view and we are able to piece the story together.  Bierce does this to disorient the reader.  He wants the reader to hallucinate along with him and he wants the reader to be as disoriented as he is.  This helps to push the themes of time, deception and death and dying.

This is a very interesting question. No doubt Ambrose Bierce himself considered writing the tale in chronological order but decided against it. For one thing, he would have had to sacrifice the extremely graphic and dramatic opening with the viewpoint character standing on the bridge with the noose around his neck, the sentries standing like statues, and the water rushing madly down below him. The biggest departure from chronological order occurs in the flashback which explains where Farquhar comes from and why he is about to be hanged. This flashback is handled with admirable professional skill. It blends smoothly into the opening scene, and it furnishes information the reader wants very much to know. It also makes Farquhar a real, sympathetic human being whose feelings we can appreciate. After the soldier steps off the plank and lets Farquhar's body fall between the railroad ties, the story seems to return to fairly straightforward chronological order. It is hard to see how the chronology could have been different except for putting all the explanatory material about Farquhar's sympathies and motives first--and that would have detracted seriously from the effect of this great story.

If Bierce had written this story in causal order, he would have begun with the background on Peyton Farquhar. Then he would have noted Farquhar's discussion with the Federal scout. He'd then skip ahead to Farquhar's execution. His dream occurred between the time he was in the noose until the time his neck snapped when the rope ran out of slack. To describe his hallucination/dream in a linear fashion, Bierce (or the narrator) would have had to write that in somewhere. As the board was thrown from under Farquhar's feet, his lavish hallucination would be condensed to, in actuality, a second. The narrator might have written something like, "During those fractions of a second, Farquhar envisioned his escape, a romanticized tale of heroism proving that maybe all is fair in love and war. However, at the fantasy's climax, the rope snapped him back into the reality of his death."

That being said, Bierce could have chosen to wait until the end to reveal that this was a hallucination; he could have done this with the story in linear order or out of order. But writing the story out of order does play with the idea of time. Farquhar's hallucination, which seems to take place over many hours, actually occurs over a matter of seconds or minutes. 

In keeping the elements out of temporal order, the narrator gives the reader a sense of things being out of time; the reader can more easily become immersed in Farquhar's fantasy.

Prior to the ending, the reader could interpret certain sentences to indicate that Farquhar's escape is in his mind. One of these instances occurs at the end of Part I:

As these thoughts, which have here to be set down in words, were flashed into the doomed man's brain rather than evolved from it, the captain nodded to the sergeant. The sergeant stepped aside. 

This does seem like a clue that "these thoughts" indicate Farquhar's escape is (will be) in his mind. But this is interrupted by Part II. 

Perhaps most importantly, by placing the background section (Part II) in between the moment the sergeant gives the order and the moment Farquhar falls to be hanged, a temporal space is created. The reader literally has to wait, the time it takes to read Part II, for a duration between the order to hang him and that order to be carried out. This gives the reader a real sense of time between the order and the hanging. This is the stretched out time of Farquhar's hallucination. A flashback or a vision (hallucination/dream) can be detailed and elaborate but in a narrative, each can be condensed to a few moments in "real time." The non-linear structure helps establish this idea.