John William, Duke of Saxe-Weimar

Johann Wilhelm was a duke of Saxe-Weimar who became heavily involved in Imperial politics after his brother Johann Friedrich II was imprisoned. Although expected to defend Protestant interests, he alienated both the Emperor and his subjects by serving as a general for the Catholic king Charles IX of France in campaigns against the Huguenots. His political missteps led to Imperial distrust and resulted in the Division of Erfurt (1572), which split the duchy into three parts between him and his brother's two sons. Johann Wilhelm retained Weimar and gained Altenburg, Gotha, and Meiningen, but lost other territories.