Hello, Alison, @ Possen: there is only al village called Possen in Thuringia. So it must be the province Posen, 1815-1919 a province of Prussia (after 1871 part German Reich "Deutsches Reich").
In most regions of this Province polish inhabitants were in majority, in some regions the German inhabitants.
In the "Regierungsbezirk" Posen 33% were Germans, in the Regierungsbezirk Bromberg 49 % were Germans (in 1900).
Germans dominated most cities, polish people lived more in villages.
So the konfession is one tip (polish=katholic about 70-80%; protestant=german ca. 90%)
the other tip is the family name, but also that is not sure, because of marriages. A person can be called Schmidt, but the children spoke polish with their mother.
So don't care the nationality, search the ancestors. Perhaps you will find the origine.