Karl Wilhelm Ferdinand Brunswick, Duke of (1735-1806), German general, was born on the 9th of October 1735 at Wolfenbüttel. He received an unusually wide and thorough education, and travelled in his youth in Holland, France and various parts of Germany. His first military experience was in the North German campaign of 1757, under the duke of Cumberland. At the battle of Hastenbeck he won great renown by a gallant charge at the head of an infantry brigade; and upon the capitulation of Kloster Zeven he was easily persuaded by his uncle Ferdinand of Brunswick, who succeeded Cumberland, to continue in the war as a general officer. The exploits of the hereditary prince, as he was called, soon gained him further reputation, and he became an acknowledged master of irregular warfare. In pitched battles, and in particular at Minden and Warburg, he proved himself an excellent subordinate. After the close of the Seven Years' War, the prince visited England with his bride, the daughter of Frederick, prince of Wales, and in 1766 he went to France, being received both by his allies and his late enemies with every token of respect.
In Paris he made the acquaintance of Marmontel; in Switzerland, whither he continued his tour, that of Voltaire; and in Rome , where he remained for a long time, he explored the antiquities of the city under the guidance of Winckelmann. After a visit to Naples he returned to Paris, and thence, with his wife, to Brunswick. His services to the dukedom during the next few years were of the greatest value; with the assistance of the minister Féronce von Rotenkreuz he rescued the state from the bankruptcy into which the war had brought it. His popularity was unbounded, and when he succeeded his father, Duke Karl I., in 1780, he soon became known as a model to sovereigns. He was perhaps the best representative of the benevolent despot of the 18th century - wise, economical, prudent and kindly. His habitual caution, if it induced him on some occasions to leave reforms uncompleted, at any rate saved him from the failures which marred the efforts of so many liberal princes of his time. He strove to keep his duchy from all foreign entanglements.
At the same time he continued to render important services to the king of Prussia, for whom he had fought in the Seven Years' War; he was a Prussian field marshal, and was at pains to make the regiment of which he was colonel a model one, and he was frequently engaged in diplomatic and other state affairs. He resembled his uncle Frederick the Great in many ways, but he lacked the supreme resolution of the king, and in civil as in military affairs was prone to excessive caution. As an enthusiastic adherent of the Germanic and anti-Austrian policy of Prussia he joined the Fürstenbund, in which, as he now had the reputation of being the best soldier of his time, he was the destined commander-in-chief of the federal army.
Between 1763 and 1787 his only military service had been in the brief War of the Bavarian Succession; in the latter year, however, the Duke, as a Prussian field marshal, led the army which invaded Holland. His success was rapid, complete and almost bloodless, and in the eyes of contemporaires the campaign appeared as an example of perfect generalship. Five years later Brunswick was appointed to the command of the allied Austrian and German army assembled to invade France and crush the Revolution. In this task he knew that he must encounter more than a formal resistance. He was so far in acknowledged sympathy with French hopes of reform, that when he gave an asylum in his duchy to the "comte de Lille" (Louis XVIII.) the revolutionary government made no protest. Indeed, earlier this year (1792) he had been offered supreme command of the French army. As the king of Prussia took the field with Brunswick's army, the duke felt bound as a soldier to treat his wishes as actual orders. (For the events of the Valmy campaign see French Revolutionary Wars). The result of Brunswick's cautious advance on Paris was the cannonade of Valmy followed by a retreat of the allies.
The following campaign of 1793 showed his perhaps at his best as a careful and exact general; even the fiery Hoche, with the "nation in arms" behind him, failed to make any impression on the veteran leader of the allies. But difficulties and disagreements at headquarters multiplied, and when Brunswick found himself unable to move or direct his army without interference from the king, he laid down his command and returned to govern his duchy. He did not, however, withdraw entirely from Prussian service, and in 1803 he carried out a successful and diplomatic mission to Russia. In 1806, at the personal request of Queen Louise of Prussia, he consented to command the Prussian army, but here again the presence of the king of Prussia and the conflicting views of numerous advisers of high rank proved fatal. At the battle of Auerstadt the old duke was mortally wounded. Carried for nearly a month in the midst of the routed Prussian army he died at last on the 10th of November 1806 at Ottensen near Hamburg.
His son and successor, Friedrich Wilhelm (1771-1815), who was one of the bitterest opponents of Napoleonic domination in Germany, took part in the war of 1809 at the head of a corps of partisans; fled to England after the battle of Wagram, and returned to Brunswick in 1813, where he raised fresh troops. He was killed at the battle of Quatre Bras on the 16th of June 1815.
See Lord Fitzmaurice, Charles W.F., duke of Brunswick (London, 1901); memoir in Allgemeine deutsche Biographie, vol. ii. (Leipzig, 1882); and, for an interesting sketch of his military character, A. Chuquet, Les Guerres de la Révolution - La Premiére Invasion prussienne (Paris, N.D.).