Short answers, pulled from the story.
Ambrose Bierce was an American author, journalist, and poet born on the 24th of June, 1842, in Meigs County, Ohio. He is best known for The Devil's Dictionary, the war story "An Occurrence at Owl Creek Bridge," and his mysterious disappearance in Mexico around 1913-1914.
Bierce crossed into Mexico at El Paso in late 1913, joined Pancho Villa's army as an observer, and wrote his last known letter from Chihuahua on the 26th of December, 1913. His fate was never confirmed, though oral tradition in Sierra Mojada, Coahuila, holds that he was executed by a Huertista firing squad.
The Devil's Dictionary is a satirical collection of definitions of English words that lampoons cant and political double-talk. It was first published in book form in 1906 as The Cynic's Word Book and was described by contemporaries as "howlingly funny." The American Revolution Bicentennial Administration named it one of the 100 Greatest Masterpieces of American Literature.
Bierce served in the Union Army's 9th Indiana Infantry and fought at Shiloh, Rich Mountain, Philippi, and Kennesaw Mountain, where he suffered a traumatic brain injury in June 1864. His grimly realistic cycle of 25 war stories, drawn from that experience, has been called the greatest anti-war document in American literature.
In January 1896, Hearst dispatched Bierce to Washington, D.C., to expose a congressional bill that would have forgiven $130 million in government loans to the Union Pacific and Central Pacific railroads. Bierce's public shaming of Collis P. Huntington on the Capitol steps, and his ongoing coverage, generated enough public opposition to defeat the bill.
Bierce's stories "Haita the Shepherd" and "An Inhabitant of Carcosa" introduced names and locations, including Hastur, Carcosa, and Lake Hali, that Robert W. Chambers used in The King in Yellow in 1895. Chambers in turn influenced H. P. Lovecraft, who called Bierce's fiction "grim and savage" and noted nearly all of it belongs to the horror genre.