"Wilhelm was the fifth (but third surviving) son of Johann, Duke of Saxe-Weimar, and Dorothea Maria of Anhalt. He was brother to Bernard of Saxe-Weimar, a successful Protestant general in the Thirty Years´ War, and to Ernest I, Duke of Saxe-Gotha (later Altenburg), a successful and well regarded ruler known as "The Pious"." - (en.wikipedia.org 16.11.2019)
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