My guess would be the drastic collapse of the Habsburg Empire in 1918. Today's little Austria is a successor state to the Habsburg Empire that once led the German Empire, dominated Europe and spanned the New World.

Imagine if Great Britain had been soundly defeated in 1918 and forced not only to abandon its empire but to break up into Ireland (whole of), Scotland (to furthest extent and then some), Wales, Cornwall, and every little region with ambitions. Leaving London with a crippled little state, unable to even lord it over the neighbours, having to take orders from Edinbourgh or be the target of punishment expeditions.

How much hate, bile and longing for the old world would that little England produce?

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