Short answers, pulled from the story.
An Occurrence at Owl Creek Bridge was first published on the 13th of July, 1890, in the San Francisco Examiner. It was later collected in Bierce's anthology Tales of Soldiers and Civilians in 1891.
At the end of An Occurrence at Owl Creek Bridge, it is revealed that Peyton Farquhar never escaped. His entire journey through the forest and back to his home was a hallucination that occurred in the instant between being dropped from the bridge and the noose breaking his neck. His dead body hangs from the bridge throughout.
Bierce used the technique of false narrative continuation, leading the reader to believe a character's escape is real when it is not. The story is also considered an early example of stream-of-consciousness narration, abandoning strict linear storytelling in favor of the internal mind of the protagonist.
Writing in 2005, Kurt Vonnegut called An Occurrence at Owl Creek Bridge the greatest American short story. He compared it to Duke Ellington's Sophisticated Lady and the Franklin stove as a flawless example of American genius.
Robert Enrico's 1962 French film adaptation won Best Short Subject at the Cannes Film Festival and the 1963 Academy Award for Live Action Short Film. The 1990 film Jacob's Ladder was directly inspired by Enrico's adaptation, with both director Adrian Lyne and writer Bruce Joel Rubin citing it as a major influence.
The story is set at a railroad bridge in northern Alabama during the American Civil War. Bierce changed the location from the real Owl Creek Bridge, which is in Tennessee, because the actual bridge had no railroad near it at the time the story takes place.