Charles William Ferdinand (; 9 October 1735 – 10 November 1806) was the Prince of Brunswick-Wolfenbüttel and Duke of Brunswick-Lüneburg and a military leader. His titles are usually shortened to Duke of Brunswick in English-language sources. He succeeded his father as sovereign prince of the Principality of Brunswick-Wolfenbüttel, one of the princely states of the Holy Roman Empire. The duke was a cultured and benevolent despot in the model of his uncle, Frederick the Great, and was married to Princess Augusta, the eldest sister of George III of Great Britain. He was also a recognized master of 18th century warfare, serving as a Field Marshal in the Prussian Army. During the Napoleonic Wars, he was mortally wounded by a musket ball at the Battle of Jena–Auerstedt in 1806. Early life Charles William Ferdinand was born in the town of Wolfenbüttel on 9 October 1735, probably in Wolfenbüttel Castle. He was the first-born son of Charles I, Duke of Brunswick-Wolfenbüttel and his wife Philippine Charlotte. His father Charles I was the ruling prince () of the small state of Brunswick-Wolfenbüttel, one of the imperial states of the Holy Roman Empire. Philippine Charlotte was the favourite daughter of King Frederick William I of Prussia and sister of Frederick II of Prussia (Frederick the Great). As the heir apparent of a sovereign prince, Charles William Ferdinand received the title of Hereditary Prince (). He received an unusually wide and thorough education, overseen by his mother. In his youth he travelled in the Netherlands, France and various parts of Germany. In 1753, his father moved the capital of the principality back to Brunswick (), the state's largest city. (Wolfenbüttel had been the capital since 1432.) The royal family moved into the newly built Brunswick Palace. Early military career Charles William Ferdinand entered the military, serving during the Seven Years' War of 1756–63. He joined the allied north-German forces of the Hanoverian Army of Observation, whose task was to protect Hanover (in personal union with the Kingdom of Great Britain) and the surrounding states from invasion by the French. The force was initially commanded by the Anglo-Hanoverian Prince William, Duke of Cumberland. At the Battle of Hastenbeck (1757) Charles William Ferdinand led a charge at the head of an infantry brigade, an action which gained him some renown. The subsequent French Invasion of Hanover and Convention of Klosterzeven of 1757 temporarily knocked Hanover out of