The connection between one's country and one's language is taken for granted by most of us. We assume that someone in France speaks French, someone in Germany speaks German, someone in Poland speaks Polish, and so on. While not always foolproof, this is now a fairly safe statement for many countries. However, when dealing with our ancestors, one must be careful about making assumptions about the languages they spoke. Empires like Prussia, Russia and Austria encompassed many different ethnic groups speaking as many different languages. For those researching Polish ancestors, it is not uncommon to find the country of origin listed as Prussia (or Germany), Russia or Austria, since all three empires controlled parts of what is now Poland from 1815 to the end of World War I. A map of Europe in 1815 shows how the current territory of Poland was divided between these three powers. Warsaw was in the Russian Empire, Krakow (Cracow) in the Austrian Empire, and Gdansk (Danzig) and Wrocław (Breslau) in the Prussian/German Empire. Borders change over time and thus depending on the. time period you may get different answers to questions of origin.
Take Walter Barney Szeszycki. Based solely on citizenship documents, you might assume that as a former subject of Germany he may have primarily been a speaker of German.
However, other evidence shows that this was not the case. The above document is no reason to discount family traditions which have always ascribed Barney with a Polish identity. The surname is decidedly Polish and not German (note that names can be tricky and may not always match with identities and languages). Finally, other documents provide clear support for Barney as a speaker of Polish. His church marriage record is much more specific about his place of origin, giving a village and the province of Posen.
The Province of Posen, although a part of Prussia and later the German Empire, had a Polish ethnic majority. Any doubt about Barney's language can be eliminated by examining census records. Some later censuses provide information not only about the place of birth but also about mother tongue. Documents after WWI show a shift from Germany to Poland as the place of birth and clear mention of Polish as Barney's mother tongue, as can be seen in the 1920 census.
The question of what languages our ancestors spoke can be a complicated one. We should always be careful about the assumptions we make about them. Clues about your ancestors' languages can be uncovered by doing research about the places they lived and about the origin of their surnames in addition to an exhaustive examination of the available documents. Special care needs to be taken when dealing with ancestors from certain parts of the world, such as Central and Eastern Europe.