They were pessimistic there would be more.
- over multiple continents - with huge number of countries participating - at the same time - as part of the same conflict
The French Revolutionary Wars/Napoleonic Wars were equally grand in scale, and conducted at a time when the "world" for all practical purposes included only European powers--all of the major ones got involved in those conflicts at one point or another; even the newly-independent US got peripherally involved (the War of 1812 is partially started due to the effects the Napoleonic Wars had on US shipping).
The United States, Canada, Japan, New Zealand, and Australia all entered the war.
There were significant theaters of the war in Africa and the Middle East.
China was initially neutral in WWI but did eventually declare support for the Entente and sent 140,000 laborers to Europe. [1]
Brazil entered the war after losing ships to German U boats. [2]
Over a million Indian troops participated. [3]
Thailand, New Guinea, and Samoa were involved [4]
And I’m just scratching the surface. The very worst fighting was concentrated in the industrial meat grinders of the front lines in Europe but there was significant participation from all corners of the earth. It earned the name “World War.”
1. https://en.m.wikipedia.org/wiki/China_during_World_War_I
2. https://en.m.wikipedia.org/wiki/Brazil_during_World_War_I
3. https://en.m.wikipedia.org/wiki/Indian_Army_during_World_War...
4. https://en.m.wikipedia.org/wiki/Asian_and_Pacific_theatre_of...
Why though? I think even China alone had almost as large a population in 1800 (300M) as the US does right now so I'm confused what this is supposed to mean? Japan also had some 30M, Russia 35M. (I haven't checked other countries.)
We're defining "the world" in 1800 to be "European powers" so that we can claim the first world war was actually before World War I?
That only made sense after WWII.
[1] Kid-detective series where the titular character, Leroy "Encyclopedia" Brown, solves crimes by finding inconsistencies that require domain knowledge https://en.wikipedia.org/wiki/Encyclopedia_Brown
https://brownencyclopedia.tumblr.com/post/13020192322/the-ca...
Imagine a world where there is no Python programming language. One day you arrive at your office and find a python (the reptile) on your desk. You would probably say, "found a python at my desk". But if that were to happen today, I am sure pictures of it would be taken and circulated within the team with captions like, "An actual Python workspace".
The presence of the word "actual" is the clue that the term is well established in the engineering world and that it is an attempt at humour.