I was checking the political party affiliations of the chancellors of the 2nd Reich, and it appears that until the later years of World War 1, all of them were politically independent. This is in contrast to the other big constitutional monarchy of the time, United Kingdom, the prime ministers of which always had a political affiliation.
So why were Imperial Germany's chancellors consistently independent? Did the Kaisers, who appointed the chancellors, simply wish it that way? Or did the law require it to be so? And if it's simply due to the inclination of the emperors, are there any written words on this "tradition", so to say, by any of the 2nd Reich's emperors?