Almost immediately after Hans succeeded his father as the Kaiser, he declared that he would be annexing the Kingdom of Poland, which lied on the eastern border of the German Reich. The reasoning for this was simple, by now there were enough german citizens living in Poland, who had migrated there after the crusade to help rebuild, that it could be considered a semi-german state.
Thus, Hans planned to annex the territory in its entirety, and Germanize its Slavic population throughout his reign as Kaiser. After all, one of his brides was a Polish Princess, and she had already been thoroughly Germanized.