Technically, not alone. His collaborator on the script was Clara Genevieve Kennedy. O. Henry was a New York writer, (technically, he was originally from No. Carolina then Texas) and the silent film “You’re Fired” was based on O. Henry’s short story, “The Halberdier of the Little Rheinschloss.” The 50-minute 5-reeler came out in 1919, some nine years after his death.
If you think O. Henry was a nom de plume, you are of course 100% on the mark. The surprise endings in all those stories were brought to you courtesy of William Sidney Porter, who also occasionally referred to himself as Olivier Henry or Oliver Henry. The O. stuck.
O. Henry is well-known, but perhaps best for The Gift of the Magi, a story about the vicissitudes of marriage and gifting that has made its way into school curriculae over the years.
As to the “You’re Fired” film’s Russian connections, it appears they are real (or pun intended reel.) It seems the film was long considered to be lost, until it surfaced at the Gosfilmofond film archive in Russia. It was brought home in 2010.