The word civilizations, used in the plural, actually implies, quite strongly, large imperial empires.Always has, always will.Its just a euphemism for imperialism, really.
For run of the mill commonplace acts of naked dominance against other humans and against Nature, but done this time large, on a grandest of scale.
Large expansionist empires divided geographically and ethnically, with a central core of privilege and an outer core of the not privileged.
And throughout the entire empire slash civilization an unequal social hierarchy of one powerful and well off class at the top and other poorer, less powerful classes way below.
At the start of WWI, the term 'civilizations' were mostly limited to places in Europe, with only Sweden and Switzerland among the fully sovereign countries without empires and hence not having a civilization to export to needy darkies.
Even more importantly,in this expanded sense of Europe, only Russia, the Ottomans and Austria-Hungary were empires without overseas possessions.
Even the regarded as not fully civilized Americans had overseas colonies.
Overseas colonies many many miles of ocean waters away satisfied the progressive Era mind.They liked a clear - if highly artificial - separation in every thing.A clear separation between the darkie subjects over there and the whitey rulers over here.
While in the older style of civilization cum empire, a subject could move more easily over land to the centre core with no realistic border barriers at ports of entry, and then hope to pass as a ruler.
Civilized behavior - courtly behavior - genteel - gentlemanly : again all these words are but euphemisms for the fact that every civilization absolutely needed an aristocracy and a hierarchy of the privileged master top and the subjugated subject bottom to qualify as a civilization rather than just a nation or a culture.
It was absolutely true when Churchill said we were defending Western Civilization --- more's the pity ....
Remember this well whenever you hear WWII propaganda claiming the Allies were defending civilization.They were indeed --- but was that actually something to be proud of ?
Wouldn't defending democracy and civil rights be something more of what the world might actually rally around. Except of course then, defeating Germany's empire would mean also breaking up the British and French empires....