This was a fun one to research!
I believe the Civil War connection is through the author's parents/grandparents. This short story, which was eerily prophetic about the fate of the
Titanic, was written by Thornton Jenkins Hains under the pen name Mayn Clew Garnett.
His father was General Peter Conover Hains, who graduated from West Point in June 1861, and had a distinguished career as a military officer that spanned from the Civil War to WWI. During the Civil War, he was both an artillery and engineering officer, participated in numerous engagements, and was cited for gallantry for his work during the siege of Vicksburg.
His mother was the daughter of Rear Admiral Thornton Jenkins. Jenkins had a long-standing military career, as well, in the Navy, which was capped by being one of Farragut's captains during the Civil War.
Thornton Jenkins Hains is an interesting guy in his own right, though. He was a self-styled sea adventure novelist, claiming to be an heir to the literary tradition of Conrad and Melville. Quite a weighty claim!
But he and his brother were mixed up in a notorious 1908 murder scandal. Thornton stood guard while his brother shot the guy who brother dearest suspected of having an affair with said brother's wife. The murder took place during a yachting club regatta in front of a bunch of witnesses. The resulting scandal is why he was reduced to writing for pulp magazines under a pen name.
I'm a true crime connoisseur (from a distance!) but was unaware of the so-called Regatta Murder, but it makes for some fascinating reading, especially in regard to the trial and the effect it had on the criminal justice system. Brother Dearest's defense was "Dementia Americana," and Thornton's was "dual insanity". . . .
Sources:
http://www.arlingtoncemetery.net/pchains.htm (General Hains bio)
http://destroyerhistory.org/fletcherclass/ns_jenkins/ (Admiral Jenkins bio)
https://www.findagrave.com/memorial/25540772/thornton-jenkins-hains (Thornton Jenkins Hains bio)
https://www.nytimes.com/2008/08/10/nyregion/thecity/10law.html (article about murder and trial)