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Your search for Who first used the term realpolitik returned the following results:

Ludwig von Rochau

The idea of prioritising pragmatic national interests - realpolitik, in the term coined by Ludwig von Rochau - is nothing new in US foreign policy, of course.

Henry Kissinger

Henry Kissinger was a proponent of Realpolitik, and played a great role in the U.S. foreign policy between 1969 and 1977.

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this famous Otto Von Bismarck

Somewhere, this famous Otto Von Bismarck quote evolved into “realpolitik’s not about what’s right

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Machiavelli

Machiavelli is seen as being one of the first proponents of realpolitik and modern philosophy.

Chancellor Otto Von Bismarck

Chancellor Otto Von Bismarck was the inventor of “Realpolitik”: a political philosophy that insisted on being completely pragmatic and realistic, rather than pursuing empty goals like “glory” or pulling punches in the name of moral rectitude.