That's the question, when did "The Great War" get named "World War I"?
I'm assuming it must have been at least after WWII started.
That's the question, when did "The Great War" get named "World War I"?
I'm assuming it must have been at least after WWII started.
The first public use of the phrase "First World War" seems to have been in the title of memoirs published in 1920, and the first public use of the phrase "World War 1" is generally accepted to have been by Time Magazine in June 1939. However, this still doesn't quite answer the question. In 1920, and even in 1939, the term "The Great War" was still far more common in general use.
Interestingly, various people have done analyses to discover when the terms "First World War" and "World War 1" became more popular than "The Great War" in general use. I wasn't able to find one that would stand up to rigorous academic scrutiny (sources of potential bias in the data are obvious in every example I found), but this article does contain a nice interactive graph.
The suggestion is that use of "First World War" and "World War 1" overtook the phrase "The Great War" in general use in about 1941.
The first known use of the phrase "The First World War" in any context is actually in an officer's diary from 1918. The diary records a conversation between officers where they discussed what historians should call the war. Obviously, however, this was not a "public" document.
Another interesting point from that article is that, even as late as January 1959, the "Second World War" was often referred to as "The Second Great War".
According to Google ngrams, "first world war" started to overtake "great war" more or less right after the end of WW2. None of "world war 1/i", "world war 2/ii", "ww1", or "ww2" show up in significant numbers compared to these terms. Not all of the "great war" hits refer to WW1, as the numbers are substantial well before 1914!
Here are some plots (note 'English' versus 'British english' corpus):
The existing answers ignore the fact that the term "The World War" was used already during the war itself and even though maybe less commonly than "The Great War", it was not rare at all. In fact "The Great War" was used even before WW1 as a name for other conflicts.
The need to add a distinguishing "First" only emerged when the possibility of another world war was being discussed and especially when the second world war started out. However, the "The World War" name itself was quite common already during WW1.
You can read the "King's Complete History of the World War" (1922), or The 110th Infantry in the World War (1919).
The term was used also in other languages and in some of them it was much more popular than the equivalent of "The Great War". For example the famous "The Good Soldier Švejk", the title in full would actually be "The Fateful Adventures of the Good Soldier Švejk During the World War" ("... za světové války"). Published from 1921 to 1923.
And in German:
I think Russell Borogove approach is correct. But the change of concept is sensitive for each country. While you look in english is natural that the change occurs during world war two, because for english speaking people both wars were important. I mean, when world war two becomes an important war as the first one, then the change happens in english.
But, for France the change is far later in time. In 1960 decade. Why? Because for France the first world war was more important than the second one, hence for them, first world war was still the "grande guerre" for a long time.
While if you look in a neutral language, like spanish (no spanish speaking country was affected by the war). The change is almost inmediate ("primera guerra" is "first world war"), during the second world war.