Sylvia Plath’s father was born in 1885 in Prussia, in the German Empire, and those are two separate things, and “Germany” a third. Let this map explain Otto Plath’s Prussia and maybe Sylvia’s references to it.
Otto was born to German parents and grew up in the area the
map labels “Posen,” territory Prussia had seized from Poland.
The component parts unified as the “German
Empire” in 1871, and for 40-plus years the Empire looked like this (Prussia in green):
Prussia was the Empire's biggest, richest, most productive state because 1) Its government and military had long been organized while other states suffered the whims of kings and dukes, and 2) Rather than exterminate Jews, Poles, and other ethnic groups, Prussia had them work to build a better Prussia, with hospitals, industry, a thriving middle class, welfare and so on. Prussia hand-picked the best and made them bureaucrats and officers so none could fight Prussia without fighting their own.
When Sylvia referred in the poem “Little Fugue” to her father’s “Prussian mind” she meant strict, focused, righteous, keen and authoritarian. Her admiration included some fear. Otto yelled a lot. It was his way or no way. She called this “Prussian” and “German” behavior, as we might, but that is only partly correct.
The German Empire’s first chancellor, Otto von Bismarck, decided to model the whole German Empire on successful Prussia
and its values – with one exception. Because the Empire ought to be German
only, non-Germans such as Jews, Poles, and Russians were to be Germanized or forcibly marched over the borders and out.
That’s not authoritarian; that’s totalitarian.
That wasn’t “Prussian”; rather, it was Teutonic, referencing
the Crusaders who around 1250 C.E. – their flag was black and white – did God’s will and crushed the North Baltic pagan Prussians, and imposed their rigid, exacting, Christian monastic and
male-dominated culture. Its advantage: Nobles were no better than anybody else.
Bismarck’s expulsions destabilized the new Empire and the rest of Europe labeled Germans evil and barbaric, and an estimated 1.5 million citizens and residents, including Prussian-educated Otto, fled the Empire for the United States.
You know the rest. The Empire within 40 years lost a war, shrank to an impoverished “Germany,” and Prussia (no relation to Russia) went extinct; it hasn’t
been on a map since 1918. New borders made Otto’s birthplace, Grabow, suddenly a Polish town. On at least one document Otto gave his birthplace as Poland.
Understandable that Sylvia Plath and The Bell Jar's “Esther Greenwood” and
the speaker of “Daddy” had only a general idea of where their father came from.