Of Welsh origin, the family name was spelt
Cadwgan until the early 15th century. According to ''Burke's Peerage'', the family descends from: Rees ap Griffith ap Llewelyn ap Meredith Bengoch ap Howell (Lord of Penbuallt) ap Sitsylt (Lord of
Builth) ap Llewelyn (Lord of Builth) ap Cadwgan ap
Elystan Glodrydd ("The Renowned"), Prince of Fferreg, of Dol-y-Gaer,
Breconshire.
Major William Cadogan (1601–1661) was a cavalry officer in
Oliver Cromwell's army. His son
Henry Cadogan was a barrister in Dublin. His eldest son
William Cadogan was a noted soldier, politician and diplomat. He was a general in the army and fought in the
War of the Spanish Succession and also served as
Ambassador to the Netherlands and as
Master-General of the Ordnance. In 1716, he was raised to the Peerage of Great Britain as
Baron Cadogan, of Reading in the County of Berkshire, with normal remainder to the heirs male of his body. In 1718, he was further honoured when he was made
Baron Cadogan, of
Oakley in the County of Buckingham, with remainder, failing heirs male of his own, to his younger brother Charles Cadogan and the heirs male of his body, and
Viscount Caversham, in the County of Oxford, and
Earl Cadogan, in the County of Denbigh, with remainder to the heirs male of his body. These titles were also in the Peerage of Great Britain. Lord Cadogan had two daughters but no sons, so on his death in 1726, three titles—the barony of 1716, the viscountcy, and earldom—became extinct. However, he was succeeded in the barony of 1718 according to the special remainder by his brother Charles, the second Baron. He was a General of the Horse and also represented
Reading and
Newport, Isle of Wight, in the
House of Commons. Cadogan married Elizabeth, second daughter and heiress of the prominent physician and collector
Sir Hans Sloane. Through this marriage the Sloane estates in
central London came into the Cadogan family, and these have been the basis of the family wealth ever since. His son, the third Baron, sat as
Member of Parliament for
Cambridge and served as
Master of the Mint. In 1800 the earldom of Cadogan held by his uncle was revived when he was created
Viscount Chelsea, in the County of Middlesex, and
Earl Cadogan. These titles were in the Peerage of Great Britain. His youngest son, the third Earl (who succeeded his half-brother in 1832), was an
admiral in the
Royal Navy. In 1831, one year before he succeeded in the earldom, he was raised to the
Peerage of the United Kingdom in his own right as
Baron Oakley, of Caversham in the County of Oxford. He was succeeded by his eldest son, the fourth Earl. He was a
Conservative politician and served under
Lord Derby and
Benjamin Disraeli as whip,
Captain of the Yeomen of the Guard from 1866 to 1868. His eldest son, the fifth Earl, was also a noted Conservative politician. He held office under Disraeli and later
Lord Salisbury as
Under-Secretary of State for War,
Under-Secretary of State for the Colonies,
Lord Privy Seal and
Lord Lieutenant of Ireland (with a seat in the cabinet). His second son
Henry Cadogan, Viscount Chelsea, heir apparent to the earldom from 1878 to 1908, represented
Bury St Edmunds in Parliament as a Conservative, but died in 1908, seven years before his father. His only son Edward, Viscount Chelsea, died in 1910 at the age of seven. Lord Cadogan was therefore succeeded by his third but eldest surviving son, the sixth Earl. As of 2023, the titles are held by the latter's great grandson, the ninth Earl, who succeeded his father in 2023. Several other members of the Cadogan family have gained distinction.
Lady Sarah Cadogan, daughter of the first Earl of the first creation, married
Charles Lennox, 2nd Duke of Richmond, and was the mother of the famous Lennox sisters (and also the grandmother of
Charles James Fox). Sir George Cadogan, second son of the third Earl, was a general in the army. Two further members represented seats in the House of Commons.
Sir Alexander Cadogan, eighth and youngest son of the fifth Earl, was the most senior civil servant to a troubled government department (
Permanent Under-Secretary for Foreign Affairs) between 1938 and 1946, that of
World War II and his personal notes reflect his part in shaping the policies which aided the survival of Britain and its
British Empire's resources in Asia during that war. The Earls Cadogan are wealthy landowners, having planned and developed and still owning
Cadogan Estates, which covers much of
Chelsea and parts of the much smaller area of
Knightsbridge, and second only to the
Duke of Westminster as Central London's richest landlords (whose surname, Grosvenor, is also closely associated with some of the most ornate London architecture). The family seat was
Culford Park, near
Culford,
Suffolk. The rampant lion in the Earl Cadogan coat of arms is shown in the badge of
Chelsea F.C. ==Horse racing==