[143] The heiress was Lady Elizabeth Percy, daughter of the eleventh Earl of Northumberland. She was married at the age of eleven to the Earl of Ogle, son of the Duke of Newcastle, who died the following year. When fourteen her mother married her to Mr. Thynne, of Longleat, in order to preserve her from Königsmark, who was trying to marry her. As Thynne refused to fight a duel with a friend of Königsmark, who was put up to pick a quarrel with him, his assassination, while driving in Pall Mall, was arranged and duly carried out. In the ensuing trial Königsmark was acquitted of complicity, but had to fly the country. [144] Charles William Ferdinand, Duke of Brunswick-Wolfenbüttel. He was born in 1735, and married, in 1764, Princess Augusta, sister of George III. He was killed at the battle of Auerstadt in 1806. Their daughter, Caroline, married George IV. The Duchess returned to England in 1807, after the death of her husband, and died in 1813. [145] John Joshua, first Earl of Carysfort (1751–1828), only son of Sir John Proby, first Baron Carysfort. He succeeded to the title on his father’s death in 1772, and was raised to an earldom in 1789. He married, first, in 1774, Elizabeth, daughter of the Right Hon. Sir John Osborne; and, secondly, in 1787, Elizabeth, daughter of the Right Hon. George Grenville. He held the post of Minister Plenipotentiary in Berlin from 1800 until 1802. [146] Prince Ferdinand Augustus of Prussia (1730–1813), youngest brother of Frederick the Great. [147] Frederick William III. married, in 1793, Louise, daughter of Duke Charles of Mecklenburg-Strelitz. She was born in 1776, and died in 1810. Frederick William, who was son of Frederick William II. and his second wife, Princess Louise of Hesse Darmstadt, became King of Prussia in 1797. [148] Prince Henry of Prussia (1726–1802), another brother of Frederick the Great. [149] Hugh Elliot, British Minister in Dresden until 1803, when he was transferred to Naples. [150] Strict regulations were at this time in force against any voluntary visit to places in the French dominions or under the rule of the Republic. Lord Holland mentions in his _Memoirs of the Whig Party_, that to obviate this he applied for a special permit, but received no answer. As they had, however, passports from Bournonville and La Valette, the French Ministers at Berlin and Dresden, and having read a letter from Lord Grenville to Lord Carysfort saying that all would be well if they did not visit Paris, they decided to go on. This was fortunate, he says, for the Duke’s letter, which he did not receive until his return to England, gave no decided permission, while as it was they had no difficulty, on reaching Dover, in obtaining leave to land. [151] Duchess Amalia of Saxe-Weimar, a Princess of Brunswick. She married Ernest Augustus, Duke of Saxe-Weimar, who died in 1758, and acted as guardian to her infant son, Charles Augustus, who lived until 1828.