These letters announce the emergence of a new diplomatic style, the birth of what came to be known as Realpolitik, for which—interestingly—there is no apt English translation. Langenscheidt’s two-volume German–English dictionary suggests ‘practical politics, politics of realism’ but neither catches the complete idea. The following exchange of letters between Bismarck and Leopold von Gerlach constitutes a kind of practical definition of the term; do what works and serves your interests.
