Anton Graff, Portrait of Frederick the Great, oil on canvas, Charlottenburg Palace, Berlin

As king, Frederick William I of Prussia gets credit for having created a strong army and an efficient civil service, but, as a father, he left something to be desired. A crude and violent man, his chief pleasures were hunting, relaxing with his “tobacco parliament” of beer-quaffing officers, and inspecting his soldiers on the parade ground in Potsdam, which he spelled varyingly as Bostdam or Postdam. Book knowledge and cultural pursuits in general he despised as unmanly and “the work of...