Duncan Kelly at the Financial Times:
Realpolitik began as an argument about the possibilities of German unification following the European revolutions of 1848. Its originator was August Ludwig von Rochau, a radical who was jailed for his politics as a student, worked in exile as a travel writer, then returned home to Germany to become a political journalist and, eventually, a politician. In 1853 he published Grundsätze der Realpolitik (roughly translated as “Foundations of Realpolitik”), whose arguments applied particularly to the ramshackle confederation of German states. Rochau’s book suggests all the things you might think of when you hear the word Realpolitik: that politics is about power, about manoeuvring coalitions, about social forces (he focused on the rising middle class in Germany) and their capacity to influence politics, and about the power of ideas in shaping political possibilities — though it takes work to pull that out of his convoluted text.
Rochau published a second version of Realpolitik in 1869, now calling for a strong German national-liberal state able to defend itself against Bonapartist tyranny and to extricate itself from its Austro-Hungarian neighbour. It took a powerful Prussia under Otto von Bismarck make that happen — and, when it did, the German chancellor quickly became regarded as a political visionary. For admirers and critics alike, his name became synonymous withRealpolitik. And as Bew suggests, the subsequent story of Realpolitik is really one of how a historically contingent German idea became divorced from its origins, morphing into a polemical term signalling hardheaded realism (as opposed to “moralism”) about politics.
more here.