Re: Fiction
More than ten decades. Surely we would include Saki's "When William Came", which tells the story of the fall of the British Empire from the point of view of an ethnologist who missed the fall because he was busy investigating the lives of a remote tribe in Siberia.
There are others of the era from 1890 to 1910, many of which were collected together by Michael Moorcock in the anthology "Before Armageddon", which he edited back in the 1970s. They include several tales of different World War ones, written before it happened, ranging from G T Chesney's "The Battle of Dorking", which tells of the conquest of England by a joint French-Russian force to a thing called "When the New Zealander Comes" (by some obvious pseudonym that I shall treat as 'anonymous' published in Strand Magazine in 1911) which tells of an archeologist visiting the ruins of Europe.
And of course, then there are some of Moorcock's own stories, Particularly "The Warlord of the Air", "The Land Leviathan" and "The Steel Tsar" - which are the most obviously steampunk novels, although things like "The Ice Schooner", the 'Captain Bastable' stories and even 'Count Brass' probably fit into the genre if we push hard enough.