Explanation: Prussia, getting rather irritated at Napoleon’s meddling in its sphere of influence in Germany, declared war on France without consulting its allies or making a deeper plan than “Fight Old Boney” in 1806. In the past decade, France had already thrown back several massive coalitions that had been arranged against it, and Napoleon himself had delivered a crushing blow to the Third Coalition consisting of most of the major powers of Europe just a few years before.

… Napoleon destroyed the entire Prussian army and took the country inside of three weeks.