Complex sentence: The Dukes of Bavaria, Württemberg, and Saxony made themselves Kings, as did the Duke of Brunswick-Lüneburg, who was already King of Great Britain; meanwhile, the Margrave of Baden elevated himself to the Grand-Ducal dignity.
Split into simpler sentences: The Dukes of Bavaria, Württemberg, and Saxony made themselves Kings, as later did the Duke of Brunswick-Lüneburg, who was already King of Great Britain. Meanwhile, the Margrave of Baden elevated himself to the Grand-Ducal dignity.