Original: Established in 1672 for Bernhard , fourth son of Wilhelm , Duke of Saxe-Weimar , Saxe-Jena was reincorporated into Saxe-Weimar on the extinction of Bernhard 's line in 1690 .
Simplified: Part of the Duchy of Saxe-Weimar was given to Bernhard , the fourth son of Wilhelm , Duke of Saxe-Weimar in 1672 .