While written a mere eight years after the war ended, H. P. Lovecraft’s still uses the Great War in the most general and allusive way possible.
The story is an updating of Edgar Allan Poe’s “Facts in the Case of M. Valdemar”. In that story, a man’s consciousness exists post-mortem and in his body because of an experiment in mesmerism.
Lovecraft’s brilliant Dr. Munoz has achieved the same effect and “lived” past his death 18 years ago by keeping his body temperature lowered with a refrigeration unit in a New York City apartment.
Dr. Munoz doesn’t look well even before his air conditioning fails, and he liquefies. (Lovecraft himself said the end derived not from Poe but Arthur Machen’s “The Novel of the White Powder”.)
Before that, though, he has a visitor:
One September day an unexpected glimpse of him induced an epileptic fit in a man who come to repair his electric desk lamp; a fit for which he prescribed effectively whilst keeping himself well out of sight. That man, oddly enough, had been through the terrors of the Great War without having incurred any fright so thorough.
It’s the most general use of World War One in a weird story — to say that the uncanniness and horror of the story exceed even the horrors of the Great War.
More entries in this series are indexed on the World War One in Fantastic Fiction page.