21 May is in May.
On 21 May 996 Otto III King Italy III King Germany III Holy Roman Emperor (age 15) succeeded III Holy Roman Emperor.
On 21 May 1108 Archbishop Gerard died.
On 21 May 1254 Conrad Hohenstaufen King Germany (age 26) died.
On 21 May 1259 Bishop Fulk Basset (age 70) died.
On 21 May 1382 Edward Hastings 8th Baron Hastings was born to Hugh Hastings 7th Baron Hastings (age 32) and Anne Despencer Baroness Hastings Baroness Marshal Baroness Morley (age 24) at Fenwick.
On 21 May 1420 the Treaty of Troyes was signed at Troyes [Map]. Thomas Beaufort 1st Duke Exeter (age 43) and Ralph Cromwell 3rd Baron Cromwell (age 17) negotiated the terms which included the marriage of Henry V (age 33) and Catherine of Valois (age 18), daughter of Charles VI (age 51), and the acknowledgement of King Henry V of England (age 33) as Charles V's (age 51) heir disinheriting the Dauphin (age 17).
Before 21 May 1524 Henry Radclyffe 2nd Earl of Sussex (age 17) and Elizabeth Howard (age 18) were married. She the daughter of Thomas Howard 2nd Duke of Norfolk (age 81) and Agnes Tilney Duchess Norfolk (age 47). He the son of Robert Radclyffe 1st Earl of Sussex (age 41) and Elizabeth Stafford Countess Sussex (age 45). He a great x 5 grandson of King Edward III of England. NOTEXT
On 21 May 1524 Thomas Howard 2nd Duke of Norfolk (age 81) died at Framlingham Castle [Map]. He was buried at Thetford Priory [Map] and subsequently reburied at the Church of St Michael the Archangel Framlingham [Map]. His son Thomas Howard 3rd Duke of Norfolk (age 51) succeeded 3rd Duke Norfolk 3C 1483, 2nd Earl Surrey 3C 1483. Elizabeth Stafford Duchess Norfolk (age 27) by marriage Duchess Norfolk.NOTEXT
On 21 May 1545 Henry Carey 1st Baron Hunsdon (age 19) and Anne Morgan Baroness Hunsdon (age 16) were married. He a great x 5 grandson of King Edward III of England.
On 21 May 1662 King Charles II of England Scotland and Ireland (age 31) and Catherine of Braganza Queen Consort England (age 23) were married at Portsmouth [Map]. She by marriage Queen Consort England. She the daughter of John IV King Portugal and Luisa de Guzman Queen Consort Portugal (age 48). He the son of King Charles I of England, Scotland and Ireland and Henrietta Maria Bourbon Queen Consort England (age 52).
On 21 May 1706 John Annesley 4th Earl Anglesey (age 30) and Henrietta Stanley Countess Anglesey (age 19) were married. She by marriage Countess Anglesey. She the daughter of William Stanley 9th Earl of Derby and Elizabeth Butler Countess Derby (age 46). He the son of James Annesley 2nd Earl Anglesey and Elizabeth Manners Countess Anglesey.
Before 21 May 1718 George Henry Lee 2nd Earl Lichfield (age 28) and Frances Hales Countess Lichfield (age 21) were married. He the son of Edward Lee 1st Earl Lichfield and Charlotte Fitzroy Countess Lichfield. He a grandson of King Charles II of England Scotland and Ireland.
Minutes of the Society of Antiquaries. 21 May 1718. Mr Alexander gave an account of an Ancient Gold Ring found at Bridewell [Map] in digging under a foundation tis a quarter of an inch broad enamelled.
Mr President (age 57) produced an old Parliament deed dated about MCCXX  sealed with the seal of the Abby of Tame, whose Abbot is an Arbitrator in a Cause between the Abbot of St Nicholas of Biddlesden [Map] and the Abbot of Oseney where he observes tis the only instance of Cistercian Order (Great Admirers of the Virgin Mary) of which the Abbot of Biddlesden was being dedicate to any other Saints.
On 21 May 1724 Robert Harley 1st Earl of Oxford and Earl Mortimer (age 62) died at Albermarle Street. His son Edward Harley 2nd Earl of Oxford and Earl Mortimer (age 34) succeeded 2nd Earl of Oxford and Earl Mortimer. Henrietta Cavendish Holles Countess of Oxford and Mortimer (age 30) by marriage Countess of Oxford and Countess Mortimer.
On 21 May 1741 Fletcher Norton 1st Baron Grantley (age 24) and Grace Chapple Baroness Grantley were married.
On 21 May 1762 James Lloyd 1st Baronet was born.
On 21 May 1772 John Singleton Copley 1st Baron Lyndhurst was born to John Singleton Copley (age 33).
On 21 May 1781 George Thicknesse 19th Baron Audley (age 24) and Elizabeth Delaval Baroness Audley (age 24) were married at St George's Church, Hanover Square. She by marriage Baroness Audley of Heighley in Staffordshire.
On 21 May 1825 Rachel Howard (age 9) died. She was buried at St Lawrence's Church, Denton.
Rachel Howard: On 11 Oct 1815 she was born to John Howard (age 34) and Elizabeth m Howard (age 33).
Thomas Bateman 1845. On the 21st of May, 1845, was opened a barrow called Carder Lowe [Map], near Hartington, which is about fourteen yards in diameter, and, owing to the former removal of its summit, is not more than two feet in average elevation. In the process of excavation about eighty quartz pebbles and several instruments of flint were found, amongst the latter a very neatly-formed barbed arrow-head. These articles were possibly cast into the mound during its construction by mourners and friends of the deceased, as tokens of respect. In addition to these were a few pieces of a coarse urn, curiously ornamented.
About the centre was found the skeleton of the chiefs over whom the barrow had been at first raised. He lay upon the right side, with the head towards the east, and the legs contracted very slightly; at his elbow lay a splendid brass or bronze dagger, in a good state of preservation. It has three large rivets remaining, which had securely attached the handle, which was still easily traceable by the wood of which it had been composed having decayed into a black mould, which contrasted strongly with the light-coloured, clayey soil in which the body was imbedded. A few inches lower down was placed a beautiful axe- or hammer-head of light-coloured basalt of much smaller size than usual, and which was originally nicely polished. Close to the head was found a small piece of calcined flint, of no apparent design or form. The skeleton was surrounded with rats' bones, the undoubted remains of those four-footed cannibals who had preyed upon the body, and had endeavoured to devour the bones of this ancient British chief, many of the latter were half-eaten away. Rather nearer to the south side of the barrow, and on a higher level, another interment was discovered, which consisted of a skeleton of mighty size, the femur or thigh-bone measuring twenty-three inches in length, which would give a height to the owner, when alive, of six feet, eight or ten inches. Along with this lengthy individual, an iron knife and three hones of sandstone were deposited; also a few pieces of calcined bone. This was evidently a secondary interment, of later date than the one previously described, which was undoubtedly the original one.
On 21 May 1871 John Campbell 9th Duke Argyll (age 25) and Princess Louise Caroline Alberta Windsor Duchess Argyll (age 23) were married. She the daughter of Prince Albert Saxe Coburg Gotha and Queen Victoria of the United Kingdom (age 51). He the son of George Douglas Campbell 8th Duke Argyll (age 48) and Elizabeth Georgiana Leveson-Gower Duchess Argyll.
On 21 May 1882 William Henry Fitzroy 6th Duke Grafton (age 62) died. His brother Augustus Charles Lennox Fitzroy 7th Duke Grafton (age 60) succeeded 7th Duke Grafton 1C 1675, 7th Earl Euston, 7th Viscount Ipswich, 7th Baron Sudbury, 8th Earl Arlington, 8th Viscount Thetford, 8th Baron Arlington of Arlington in Middlesex 1C 1665 and 8th Baron Arlington of Arlington in Middlesex 2C 1672.
On 21 May 1896 John Verney 28th Baron Latimer 20th Baron Willoughby de Broke was born to Richard Verney 27th Baron Latimer 19th Baron Willoughby de Broke (age 27).
On 21 May 1915 Lieutenant Arthur George Coke (age 33) was killed in action whilst serving with the Royal Naval Air Service. He is commemorated on the Helles Memorial at Gallipoli. Memorial at St Withburga's Church, Holkham [Map].
On 21 May 1929 Archibald Philip Primrose 5th Earl Rosebery 1st Earl Midlothian (age 82) died. His son Albert Archibald Primrose 6th Earl Rosebery 2nd Earl Midlothian (age 47) succeeded 6th Earl Rosebery, 2nd Earl Midlothian, 2nd Viscount Mentmore of Mentmore in Buckinghamshire, 2nd Baron Epsom of Hyde in Surrey.
On 21 May 2011 Henry FitzRoy St John 9th Viscount St John 8th Viscount Bolingbroke (age 54) died. His brother Nicholas St John 10th Viscount St John 9th Viscount Bolingbroke (age 36) succeeded 10th Viscount St John, 9th Viscount Bolingbroke, 13th Baronet St John Lydiard Tregoze in Wiltshire.
On 21 May 2018 John Fremantle 5th Baron Cottesloe (age 91) died. His son Thomas Henry Fremantle 6th Baron Cottesloe (age 52) succeeded 6th Baron Cottesloe of Swanbourne and Hardwick in Buckinghamshire, 6th Baronet Fremantle of Swanborne in Buckinghamshire.