Duke Frederick of Saxe-Weimar was a prince from the Ernestine branch of the House of Wettin and a Colonel in the Thirty Years' War.
17th-century engraving
Friedrich of Saxe-Altenburg was a member of the Ernestine branch of the House of Wettin and a Duke of Saxe-Altenburg and Duke of Jülich-Cleves-Berg. Friedrich is sometimes called "Friedrich the younge
