Wordorigins.org

One question that pops up on this site’s discussion forum from time to time is when did World War I get its number? When did people start to refer to that war as the first (as opposed to only)?

The term world war appears in the Westminster Gazette of 8 April 1909, in reference to a hypothetical future war involving the great nations of Europe:

This...is the type of dirigible by which in a world-war...360,000 German troops could be transported from Calais to Dover in half an hour.