"Friedrich of Saxe-Altenburg (12 February 1599, Torgau – in battle: 24 October 1625, Seelze) 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 younger" to distinguish him from Prince Frederick of Saxe-Weimar, as they were both called "Friedrich of Saxe-Weimar"." - (en.wikipedia.org 08.03.2020)
