German unification has always been a little confusing to me. Mainly around the point of the smaller/weaker states essentially giving up some amount of sovereignty to Prussia. I know Prussia was the most powerful German state at this point and there were fears of popular revolutions bringing down the various German monarchies, but it is a rare thing in history for a sovereign state to willingly surrender power to another state. I would love a book or article recommendation on this topic.
Dennis Showalter has a book called "The Wars of German Unification" that may shed some light on your question. He is a professor at Colorado College and an expert in German military.