| Johann Ernst II | |
| Succession: | Duke of Saxe-Weimar |
| Reign: | 1662 - 1683 |
| Predecessor: | William |
| Successor: | William Ernest |
| Spouse: | Christine Elisabeth of Holstein-Sonderburg |
| Issue: | Anna Dorothea, Abbess of Quedlinburg Wilhelmine Christine, Countess of Schwarzburg-Sondershausen Eleonore Sophie, Duchess of Saxe-Merseburg-Lauchstädt William Ernest, Duke of Saxe-Weimar John Ernest III, Duke of Saxe-Weimar |
| House: | Wettin |
| Father: | William, Duke of Saxe-Weimar |
| Mother: | Eleonore Dorothea of Anhalt-Dessau |
| Birth Date: | 11 September 1627 |
| Birth Place: | Weimar |
| Death Place: | Weimar |
John Ernest II (11 September 1627, in Weimar - 15 May 1683, in Weimar), was a duke of Saxe-Weimar. He was the second but eldest surviving son of William, Duke of Saxe-Weimar, and Eleonore Dorothea of Anhalt-Dessau.
After the death of his father on 1662, he became reigning duke. In 1672 John Ernest divided his possessions with his younger brothers. He retained Weimar, his brother John George I received Eisenach, and his other brother, Bernhard, received Jena. Eventually, the partitioned lands, Saxe-Weimar, Saxe-Eisenach (1741) and Saxe-Jena (1690) were re-combined.
Like his father, John Ernest was particularly interested in the arts (see Fruitbearing Society). He was also an avid hunter. Given his overriding interest in these pursuits, John Ernest entrusted the reigns of government to his chancellor.
In Weimar on 14 August 1656, John Ernest married Christine Elisabeth, (23 June 1638 - 7 June 1679), a daughter of John Christian, Duke of Schleswig-Holstein-Sonderburg (26 April 1607 - 28 June 1653).[1] They had five children:[2]
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