Interesting. What exactly did Bismarck say? It would seem that he spoke of "Ausrottung" of the problem related to there being Poles in the Posen Province rather than of the Ausrottung of the Posen Poles.
Am I right?
I have now found the passage in which Bismarck used the word "ausrotten" in relation to Poles. It occurs in a letter of 26 March 1861 to his sister Malwine, written from St Petersburg where Bismarck was Prussian Ambassador. The letter is found on page 568 of "Gesammelte Werke", XIV/I, and is quoted in Hans Rothfels, "Bismarck, der Osten und das Reich", p. 75. The passage reads:
<<Haut doch die Polen, dass sie am Leben verzagen. Ich habe alles Mitgefuehl fuer ihre Lage, aber wir koennen, wenn wir bestehn wollen, nichts andres thun, als sie AUSROTTEN; der Wolf kann nicht dafuer, dass er von Gott geschaffen ist, wie er ist, und man schiesst ihn doch dafuer todt, wenn man kann.>>
Here Bismarck definitely seems to be speaking about violent action ("hauen") directed against Poles rather than about elimination of the "Polish problem". The analogy with killing wolves is eerily similar to what Hitler said to Horthy at their Klessheim meeting in 1943.
An attempt at explaining Bismarck's words was made by William Hagen in his "Germans, Poles and Jews: The nationality Conflict in the Prussian East, 1772-1914", on page 125. Hagen writes:
In his political practice, he remained faithful to the sentiments he expressed in a letter to his sister written in 1861, while Prussian ambassador to Russia: "Flay the Poles until they despair of life! I have all sympathy for their position, but if we wish to endure, we can do nothing else but extirpate them". Bismarck meant that the Poles should be deprived of all national autonomy and forced to accept citizenship under the partitioning governments, not physically destroyed. Yet he concluded this passage with the sanguinary remark: "It is not the wolf's fault that God created him as he is, but nevertheless we kill him whenever we can".
Hagen has interpreted Bismarck's use of the word "ausrotten" in a non-homicidal way, in contrast to the usual interpretation of the use of that word by Hitler and Himmler. But that might be because there was no physical destruction of Poles when Bismarck was in power.