In an essay, the writing strategy of showing a thought process is intended to do what?

Showing the thought process is most likely made because It helps the reader reach the same conclusions as the author.
By showing the thought process, the author could show the readers about the analyzation and rationalization that he/she made when examining the data at hand. Both of these things would expose the readers to a brand new/rational perspective on the relevant subject matter.

The answer to that would be prussia which would later be germany