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Let's suppose that when Germany unifies, the Kingdom of Hanover is not annexed by Prussia fully, but admitted as a federal state of the new Empire. Such a thing isn't unheard of, Hesse lost a small amount of territory to Prussia, but was allowed to be its own member of both the North German Confederation and German Empire.

However, even if Hanover was to remain separate, they would certainly lose territory. Which regions of Hanover would be annexed to Prussia whilst retaining the kingdom?
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