Charles Seymour, 6th Duke of Somerset, KG, PC, (13 August 1662 – 2 December 1748), known by the epithet "The Proud Duke", was an English aristocrat and courtier. He rebuilt Petworth House in Sussex, the ancient Percy seat inherited from his wife, in the palatial form which survives today. According to the Encyclopædia Britannica Eleventh Edition, he was a remarkably handsome man, and inordinately fond of taking a conspicuous part in court ceremonial. His vanity, which earned him the sobriquet of "the proud duke", was a byword among his contemporaries and was the subject of numerous anecdotes; Macaulay described him as "a man in whom the pride of birth and rank amounted almost to a disease".
Charles Seymour was the second son of Charles Seymour, 2nd Baron Seymour of Trowbridge (died 1665), of Marlborough Castle in Wiltshire, by his wife Elizabeth Alington (1635–1692). The 2nd baron was (in a junior line) a great-great-grandson of Edward Seymour, 1st Duke of Somerset (executed 1552), brother of Queen Jane Seymour, uncle of King Edward VI and Lord Protector of England.
Charles was educated at Harrow School and Trinity College, Cambridge, where his portrait by Nathaniel Dance-Holland survives in the college's collection.
In 1675, Charles's elder brother Francis Seymour, 5th Duke of Somerset, aged 16, inherited the Dukedom of Somerset from their father's childless first cousin, John Seymour, 4th Duke of Somerset (1629–1675). However, the 5th Duke did not inherit the unentailed Seymour estates, including the family seat of Wulfhall and other Wiltshire estates, and much of the lands of the feudal barony of Hatch Beauchamp in Somerset, which were bequeathed to the 4th duke's niece, Elizabeth Seymour, wife of Thomas Bruce, 2nd Earl of Ailesbury (1656–1741). In 1660, following the Restoration of the Monarchy, the 4th duke's own father, a Royalist commander in the Civil War, had been restored to the dukedom created for and forfeited by his own great-grandfather, Edward Seymour, 1st Duke of Somerset (executed 1552).
Three years later, in 1678, Charles's brother, the 5th duke, was murdered in Italy, aged 20, unmarried and without progeny, having been shot at the door of his inn at Lerici. The 16-year-old Charles Seymour became the 6th duke and the 4th Baron Seymour of Trowbridge.
In 1682, at the age of 20 he married a great heiress, the 15-year-old Lady Elizabeth Percy (1667–1722), daughter and sole heiress of Joceline Percy, 11th Earl of Northumberland (1644–1670), who brought him immense estates, including Alnwick Castle, Northumberland; Petworth House, Sussex; Leconfield Castle, Yorkshire; Cockermouth Castle, Cumberland; Egremont Castle, Cumberland; Syon House, Middlesex, and Northumberland House in London. It had been agreed in the marriage settlement, although both parties to the marriage were minors, and thus legally incapable of being bound by a contract, that:
"... for the preservation of the noble family and name of the Percys, he the said duke and all and every the issue of his body on her the said duchess begotten, should forever take upon him and them and be called and named only by the name and surname of Percy".
However, on attaining her majority of 21 the duchess under her hand and seal dated 30 January 1687 consented to waive and dispense with the agreement. The intention stated in the marriage contract was however fulfilled in 1749 by their granddaughter Lady Elizabeth Seymour and her husband the former Sir Hugh Smithson, 4th Baronet (who by special remainder had inherited in 1749 his father-in-law's title Earl of Northumberland) when in 1749 they obtained a private act of Parliament entitled:
"An Act to enable Hugh Earl of Northumberland and Elizabeth Countess of Northumberland and Barones Percy, his Wife, and their Children, Progeny and Issue, to take and use the Name of Percy, and bear and quarter the Arms of the Percies Earls of Northumberland".
The reason for the name change was stated in the preamble to the act as follows:
"And as Algernon, late Duke of Somerset, did in his lifetime express his desire that the name of Percy should be used by and be the surname and family name of the Earls of Northumberland ... Sir Hugh Smithson now Earl of Northumberland and Lady Elizabeth his wife, Countess of Northumberland and Baroness Percy, as well out of their great regard to, and in compliance with the desire of, the said late duke, as for preserving the noble and ancient family and name of Percy and the coats of arms borne and quartered by the Percys Earls of Northumberland should be ... confirmed ... upon them ... by authority of Parliament".
Between 1688 and 1696 the Duke rebuilt Petworth House on a palatial scale. A painting made in about 1700 of his new house was identified by the art historian Sir Anthony Blunt in the collection of the Duke of Rutland at Belvoir Castle. It shows evidence of a French château style, with original central dome, now lost. A similar image is included in Louis Laguerre's wall-painting on the Grand Staircase at Petworth. Horace Walpole called it "in the style of the Tuileries". The parapets of the walls are surmounted by urns. On the three sections of the parapet in front of the central dome and the domed roofs of the two projecting wings are placed gesticulating statues. Today the roofline is lower and flat, giving the building a plain appearance, having been simplified later in the century due to changing tastes. The statues and urns were removed and the entrance front has been moved to the rear. One of the few elements of the old mansion he retained is the mediaeval chapel, which retains the large early 17th century Percy Window, depicting the coats of arms of several Percy Earls of Northumberland.
In 1683, Somerset received an appointment in the royal household of King Charles II and in August 1685 he was appointed Colonel of the Queen Consort's Light Dragoons when James II expanded his army after the Monmouth Rebellion. However, he fell from favour in 1687 when as Lord of the Bedchamber he refused to escort the newly appointed Papal Nuncio, Archbishop Ferdinando d'Adda and was deprived of his various offices.
At the Glorious Revolution of 1689, he supported the Prince of Orange, who became King William III. Having befriended Princess Anne in 1692, he became a favourite of hers after her accession to the throne as Queen Anne (1702–1714), and was appointed by her in 1702 Master of the Horse, a post he held until 1712. Finding himself neglected by John Churchill, 1st Duke of Marlborough, he made friends with the Tories, and succeeded in retaining the Queen's confidence, while his wife replaced Sarah Churchill, Duchess of Marlborough as Mistress of the Robes in 1711. The Duchess of Somerset became the Queen's closest confidante, causing Jonathan Swift to direct at her a violent satire, The Windsor Prophecy, in which he accused her of murdering her previous husband, Thomas Thynne (died 1682) of Longleat. The Duchess retained her influence even after the Queen, following a quarrel, dismissed the Duke as Master of the Horse in 1712.
In the memorable crisis when Anne was at the point of death, Somerset acted with John Campbell, 2nd Duke of Argyll, Charles Talbot, 1st Duke of Shrewsbury and other Whig nobles who, by insisting on their right to be present in the Privy Council, secured the Hanoverian succession to the Crown.
He retained the office of Master of the Horse for the first year of the reign of King George I (1714–1727) until 1715, when he was dismissed and retired to private life.
In 1739, the Duke became a founding governor of the Foundling Hospital in London, the country's first and only children's home for foundlings, after his second wife, Charlotte Finch (1693–1773), became the first to sign the petition to King George II of its founder Captain Thomas Coram.
The Duke died at Petworth on 2 December 1748.