John Adolphus, Duke of Schleswig-Holstein-Sonderburg-Plön, Dorothea Augusta's eldest son in around 1750The gardens of Plön Castle with the castle in the background in 1749
In 1633, she married Joachim Ernest, Duke of Schleswig-Holstein-Sonderburg-Plön. On the occasion of their marriage, Joachim Ernest built a new residence and seat of government, Plön Castle, in the seat of his duchy, the town of Plön, which was completed in 1636. The couple ruled over only a small territory, as Joachim Ernest and his four brothers had divided the duchy of their father among themselves, resulting in five small ones. Their estate included Plön, Ahrensbök and Reinfeld.
Issue
Dorothea Augusta had eight children with his husband, seven of whom survived childhood:
Duke John Adolphus of Schleswig-Holstein-Sonderburg-Plön (8 April 1634 – 2 July 1704), who became Duke of Schleswig-Holstein-Sonderburg-Plön, married Dorothea of Brunswick-Wolfenbüttel and had issue
Duke Augustus of Schleswig-Holstein-Sonderburg-Plön (9 May 1635 – 17 September 1699), who became Duke of Schleswig-Holstein-Sonderburg-Plön-Norburg, married Princess Elisabeth Charlotte of Anhalt-Harzgerode (1647–1723) and had issue
Duchess Ernestine of Schleswig-Holstein-Sonderburg-Plön (10 October 1636 – 18 March 1696)
Duke Joachim Ernest II of Schleswig-Holstein-Sonderburg-Plön (5 October 1637 – 5 October 1700), who became Duke of Schleswig-Holstein-Sonderburg-Plön-Rethwisch, who married Isabella of Merode-Westerloo (c. 1649 – 5 January 1701)
Duke Bernard of Schleswig-Holstein-Sonderburg-Plön (31 January 1639 – 13 January 1676), Danish general
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