alt Hacker NewsWWII, contemporaneously, was thought of as several small regional wars: “wow, that Hitler guy has started a bunch of small limited conflicts.”
It was only when one stood back to regard the whole picture that it became clear that something larger was happening.
OP is making the same point.
When Hitler invaded Poland, it took all of two days for basically all of Europe to realize that they were about to replay the Great War (which we now call WW1).
https://en.wikipedia.org/wiki/Declarations_of_war_during_Wor...
Of course it took longer for it to blow up into a truly global war (Pearl Harbor etc), but a conflagration across Europe is hardly a "small regional war".