Annexation of the Kingdom of Hanover by Prussia

Electors were by no means "democratic" or "elected". The Elector of Hesse-Kassel was a deeply-reactionary ruler whose repressive measures caused an unavoidable bust-up when he asked the Austrian Empire for assistance, when Prussia was much closer and more relevant (although Protestant) power. King Georg V of Hanover flew in the face of near-tearful appeals from his Council to refrain from acting against that (Protestant) Power when the bust-up came. The King was the son of one of the most detested and reviled reactionaries in Europe, whose Administration of his Kingdom, nonetheless, pleased many of his subjects. The Kingdom disappeared and took with it Ludwig Windhorst, one of Bismarck's most trenchant critics, one of the most rational politicians in Germany. This is, of course, no place for a discussion of the Schleswig-Holstein conundrum, but the Franco-Austrian War would have been far less likely to occur without a dusting of Electors to muddy the waters. (I love a mixed metaphor.).

The German unification was a drawn-out process.The Holy Roman Empire had several hundred "sovereign nations" in the middle ages, that was slowly concentrated into fewer, larger nations, and finally into one.

In the end it came down to a Lesser German Solution under the leadership of Prussia, or a Greater German Solution under the leadership of Austria with Prussia playing second fiddle. The Austro-Prussian War settled this for the Lesser German Solution.

Ever since the Napoleonic Wars, there was widespread sentiment towards unification. What the English wikipedia calls the German Campaign of 1813 are the Liberation Wars in Germany, that has a completely different ring. Patriotic Germans were ambivalent between support for their sovereign or support for the idea of Germany which transcended the petty state. The German Anthem was a desperate call for the states to unify, have a look at the first two stanzas in the context of not having a German nation.

Hanover was just the "spoil of war" for being on the losing side of the Austro-Prussian_War.

Early in the war, the Hanoverian army won a "Pyrrhic Victory" at Langensalz. This allowed it to be crushed from behind by two Prussian armies, and the Kingdom overrun. When Prussia went on to win the whole war, Hanover had no allies to rescue her.

There were no diplomatic repercussions in Britain, because Hanover had forbidden Queen Victoria to become Queen of Hanover because she was a woman in 1837. Britain's response was, "you're on your own."

France was friendly to Italy, neutral to Prussia, and hostile to Austria at the time, having sided with Italy in an 1859 war against Austria. (Italy was allied with Prussia in 1866.)

Hanover was originally an electorate which was annexed to Westphalia during the Napoleonic wars. During those times a lot of countries were roadkill on the political highway, pawns in the global political dynamic. After Napoleon was defeated the English restored Hanover as a kingdom, a completely different status.

Dictators (like kings and like Napoleon) do not particularly like free countries or oligarchies, like electorates. When you have lots of free countries around it makes you look bad if you are a dictator. Also, negotiating with free countries is difficult because there are multiple decision makers. "Erecting" the Kingdom of Hanover was kind of like the Allies making Czechoslovakia after the Great War, an artificial entity made to counterbalance Prussia.

When Prussia annexed this English-concocted Kingdom of Hanover, Napoleon III had no objections at all, stating that it contributed to the "peace of Europe". At the time, France was more concerned by the activity of Austria in the Mediterranean and the removal of Hanover as an Austrian ally reduced that threat.

An English publisher wrote the following editorial expressing the English point of view:

If Hanover were a State in any true sense of the word, the action of the King of Prussia in abolishing it would be simply oppressive, but it is not; it is simply a section of Germany, in which it was once expedient for German interests that a separate sovereign should reign, and is now expedient for German interests that he should not.

--Opinions of the Press on the annexation of Mysore (1866)