I assume "
Wilhelmine Germany" would refer to Germany under the kaiser / emperors named
Wilhelm.
I'm sure
Wilhelmine is pronounced the same way as
Wilhelmina in
German. I've never heard it pronounced in English to be honest, but I really like the way, "willa-MEEN" sounds. (I'm just thrilled when people know that the first part is "willa" not "wil-hel.")