Alan IV, Duke of Brittany of William the Bastard, Duke of Normandy (later to become known as William the Conqueror) support of rebels in Brittany against Alan's maternal uncle, Conan II. Conan II died in late 1066 during a campaign in Anjou, and was succeeded by Alan's parents, Conan's sister Hawise and her husband Hoel II. Hoel ruled as regent from Hawise's death in 1072 until Alan reached his majority in 1084. To prevent further hostilities during his invasion of England, William I married his daughter Constance to the new duke Alan in 1087. The marriage ceremonies may have taken place in Bayeux in Normandy.
William Ernest, Duke of Saxe-Weimar William Ernest, Duke of Saxe-Weimar William Ernest, Duke of Saxe-Weimar (19 October 1662 – 26 August 1728) was a duke of Saxe-Weimar. He was born in Weimar, the eldest son of Johann Ernst II, Duke of Saxe-Weimar and Princess Christine Elisabeth of Schleswig-Holstein-Sonderburg. When his father died in 1683, he succeeded him as duke; however, he was compelled to rule jointly with his younger brother Johann Ernst III. Because John Ernest III was alcoholic, William Ernest took full control of the government of the duchy and permitted John Ernest the nominal title of co-duke ("Mitherr") until his death in 1707.