Ambrose Bierce 
An Occurrence at Owl Creek Bridge [EPUB ebook] 

First published in 1800, 'An Occurrence at Owl Creek Bridge’ is a short story by the American writer and Civil War veteran Ambrose Bierce described as ’
one of the most famous and frequently anthologized stories in American literature’.
'An Occurrence at Owl Creek Bridge’ recounts the events leading up to and immediately following the hanging of a Confederate sympathizer by the Union Army. The story is story set during the Civil War and utilizes the frame story technique.
The narration is divided into three sections. The first section is written in present tense, suggesting it is the current event. The second section acts as a flashback to provide information leading up the present situation. The final section contains the frame story which, as you should recall, is a story within a story.