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 Augustus, Duke of Brunswick-Harburg France and England and then enrolled with his brothers at the University of Helmstedt. In 1594, he again went on a journey that took him through Germany, Poland, Switzerland, Italy, Holland, Denmark and Livonia. William Augustus kept a journal about his travels. After the death of his father, he took up the government of Harburg jointly with his brothers Christopher and Otto III. After they died, he ruled alone. In 1618, William Augustus began the construction of the palace at Moisburg. After the death of the Duke Frederick Ulrich of Brunswick-Wolfenbüttel, he received the County of Hoya from his inheritance.