Charles William Ferdinand 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.

The Principality of Brunswick-Wolfenbüttel was a subdivision of the Duchy of Brunswick-Lüneburg, whose history was characterised by numerous divisions and reunifications. It had an area of 3,828 square kilometres in the mid 17th century. Various dynastic lines of the House of Welf ruled Brunswick-Wolfenbüttel until the dissolution of the Holy Roman Empire in 1806. As a result of the Congress of Vienna, its successor state, the Duchy of Brunswick, was created in 1815.