“The most controversial, original and striking figure in Prussian history,” they write about King Frederick William I, the father of the legendary Frederick the Great. On the one hand, according to contemporaries, he is a “sadist”, “monster”, “fiend of hell”, "the strangler of free thought." On the other hand - and contemporaries also spoke about this - a staunch human rights activist, a fanatical champion of social justice, a genius of finance and economics, a gifted commander...Who was he, this “soldier king”? “Despot”? Or “revolutionary on the throne”? Perhaps , the book of the famous German historian Wolfgang Fenor will help answer this question...