Duke in Turkey, Afghanistan, and Iran after Mongolian war against them, was added as generals and kings of districts or states but in the Kingdom of Persians and Ottomans, the systems cannot be fully translated to its European counterparts so they called those generals and kings as Khan, a Mongolian royal and noble rank from the Turco-Mongol word for "lord," equal to Duke.
Son of Charles William Ferdinand. During the Napoleonic Wars, from 1806 to 1813, France occupied Brunswick-Wolfenbüttel. Died in battle at Quatre Bras. Frederick William's son Charles (a minor at the time of his father's death) became the first Duke of independent Brunswick. Duchy of Brunswick