Henry I of France whose death Henry was left to deal with his rebel sibling. In 1032, he placated his brother by giving him the duchy of Burgundy which his father had given him in 1016. In an early strategic move, Henry came to the rescue of his very young nephew-in-law, the newly appointed Duke William of Normandy (who would go on to become William the Conqueror), to suppress a revolt by William's vassals. In 1047, Henry secured the dukedom for William in their decisive victory over the vassals at the Battle of Val-ès-Dunes near Caen; however, Henry would later support the barons against
William IV, Grand Duke of Luxembourg William IV, Grand Duke of Luxembourg William IV (William Alexander; "French: Guillaume Alexandre"; 22 April 1852 – 25 February 1912) reigned as the Grand Duke of Luxembourg from 17 November 1905 until his death. He succeeded his father, Adolphe. William was a Protestant, the religion of the House of Nassau. He married Princess Marie Anne of Portugal, believing that a Roman Catholic country ought to have a Roman Catholic monarch. Thus his heirs have been Catholic. At the death of his uncle, Prince Nikolaus-Wilhelm in 1905, the only other legitimate male in the House of Nassau-Weilburg was William's cousin, Georg