21 Sep is in September.
1299 Edward I Creates New Barons
1348 Black Death Plague Outbreak
1397 Arrest and Execution of Richard Fitzalan 9th Earl Surrey 11th Earl Arundel
On 21 Sep 1026 Otto William Ivrea I Count Burgundy (age 66) died. His son Reginald Ivrea I Count Burgundy (age 40) succeeded I Count Burgundy. Alice Normandy Countess Burgundy (age 24) by marriage Countess Burgundy.
On 21 Sep 1250 Marie Montgomery Countess Ponthieu (age 51) died.
On 06 Feb 1299 King Edward "Longshanks" I of England (age 59) created a number of new Barons by writ of summons to Edward's 44th Parliament ...
John Ferrers 1st Baron Ferrers of Chartley (age 27) was created 1st Baron Ferrers of Chartley.
John Lovell 1st Baron Lovel (age 45) was created 1st Baron Lovel of Titchmarsh. Joan Ros Baroness Lovel (age 39) by marriage Baroness Lovel of Titchmarsh.
William Ros 1st Baron Ros Helmsley (age 44) was created 1st Baron Ros Helmsley. Maud Vaux Baroness Ros (age 42) by marriage Baroness Ros Helmsley.
William Devereux 1st Baron Devereux Lyonshall (age 55) was created 1st Baron Devereux Lyonshall. Lucy Burnell Baroness Devereux Lyonshall by marriage Baroness Devereux Lyonshall.
Adam Welles 1st Baron Welles (age 50) was created 1st Baron Welles. Joan D'Engayne Baroness Welles and Ughtred by marriage Baroness Welles.
Robert Clinton 1st Baron Clinton (age 41) was created 1st Baron Clinton. Ida Odingsells Baroness Clinton (age 34) by marriage Baroness Clinton.
John Moels 1st Baron Moels (age 30) was created 1st Baron Moels.
The next baronies may not have been created on 06 Feb 1299 but were created in 1299 possibly for Edward's 45th and 46th Parliaments on 10 Apr 1299 and 21 Sep 1299 respectively.
Edmund Deincourt 1st Baron Deincourt (age 49) was created 1st Baron Deincourt 1C 1299.
John Strange 1st Baron Strange Knockin (age 46) was created 1st Baron Strange Knockin 2C 1299. Maud Eiville Baroness Strange Knockin by marriage Baroness Strange Knockin.
John St John Lagenham 1st Baron St John Lagenham (age 49) was created 1st Baron St John Lagenham.
Robert Clifford 1st Baron Clifford (age 24) was created 1st Baron de Clifford 1C 1299. Maud Clare Baroness Clifford Baroness Welles (age 23) by marriage Baroness de Clifford.
Henry Grey 1st Baron Grey of Codnor (age 44) was created 1st Baron Grey of Codnor 1299. Eleanor Courtenay Baroness Grey Codnor by marriage Baroness Grey of Codnor 1299.
John Mohun 1st Baron Dunster (age 30) was created 1st Baron Mohun of Dunster. Ada Tiptoft Baroness Dunster (age 24) by marriage Baroness Mohun of Dunster.
Roger Scales 1st Baron Scales was created 1st Baron Scales.
John St John 1st Baron St John Basing (age 25) was created 1st Baron St John Basing.
John Beauchamp 1st Baron Beauchamp Somerset (age 24) was created 1st Baron Beauchamp Somerset.
Alan Zouche 1st Baron Zouche Ashby (age 31) was created 1st Baron Zouche Ashby.
Henry Percy 9th and 1st Baron Percy (age 25) was created 1st Baron Percy of Alnwick 1C 1299. Eleanor Fitzalan Baroness Percy (age 15) by marriage Baroness Percy of Alnwick.
William Grandison 1st Baron Grandison (age 37) was created 1st Baron Grandison 1C 1299. Sibylla Tregoz Baroness Grandison by marriage Baroness Grandison. His brother was also created Baron Grandison on the same day.
Otto Grandison 1st Baron Grandison (age 61) was created 1st Baron Grandison 1C 1299. His brother was also created Baron Grandison on the same day.
Thomas de Multon 1st Baron Multon (age 22) was created 1st Baron Multon Egremont. Eleanor Burgh Baroness Multon Egremont (age 17) by marriage Baroness Multon Egremont.
On 21 Sep 1305 Louis X King France I Navarre (age 15) and Margaret of Burgundy Queen Consort France (age 15) were married. She the daughter of Robert II Duke Burgundy (age 57) and Agnes Capet Duchess Burgundy (age 45). He the son of Philip "The Fair" IV King France (age 37) and Joan Blois I Queen Navarre. They were first cousin once removed. He a great x 4 grandson of King Henry "Curtmantle" II of England. She a great x 3 granddaughter of King Henry "Curtmantle" II of England. 
On 21 Sep 1327 King Edward II of England (age 43) was murdered at Berkeley Castle [Map]. There is speculation as to the manner of his death, and as to whether he died at all. Some believe he may have lived the rest of his life in Europe.
After 21 Sep 1327 King Edward II of England (age 43) was buried at Gloucester Cathedral [Map].
Before 21 Sep 1349 Hugh Fitzhugh Fitzhenry (age 15) died. Possibly by plague given the 1348 Black Death Plague Outbreak occurring at this time.
On 21 Sep 1371 John of Gaunt 1st Duke Lancaster (age 31) and Constance of Castile Duchess of Lancaster (age 17) were married at Roquefort, Landes. She by marriage Duchess Lancaster. His younger brother Edmund of Langley 1st Duke York (age 30) married Constance's sister in July 1372. She the daughter of Peter "Cruel" I King Castile and Maria Padilla. He the son of King Edward III of England (age 58) and Philippa of Hainault Queen Consort England.
On 21 Sep 1371 Frederick I Elector Brandenburg was born to Frederick Hohenzollern V Burgrave Nuremburg (age 38).
On 21 Sep 1375 William Stafford 4th Earl Stafford was born to Hugh Stafford 2nd Earl Stafford (age 39) and Philippa Beauchamp Countess Stafford (age 41). He a great x 3 grandson of King Edward "Longshanks" I of England.
On 21 Sep 1397 Richard Fitzalan 9th Earl Surrey 11th Earl Arundel (age 51) was tried at Westminster [Map].
He was beheaded at Tower Hill [Map] immediately thereafter. Earl Surrey 1C 1088 and Earl Arundel Sussex forfeit.
On 21 Sep 1411 Richard Plantagenet 3rd Duke York was born to Richard of Conisbrough 1st Earl Cambridge (age 26) and Anne Mortimer (age 20). His mother died shortly afterwards. He a great grandson of King Edward III of England. Coefficient of inbreeding 2.28%. 
After 21 Sep 1411 Anne Mortimer (age 20) died from childbirth. Her son Richard Plantagenet 3rd Duke York succeeded Heir to the Throne of England, 8th Earl Ulster.
After 21 Sep 1411 Richard of Conisbrough 1st Earl Cambridge (age 26) and Maud Clifford Countess Cambridge (age 22) were married. He the son of Edmund of Langley 1st Duke York and Isabella of Castile Duchess York. He a grandson of King Edward III of England. She a great x 4 granddaughter of King Edward "Longshanks" I of England.
On 21 Sep 1415 Frederick "Peaceful or Fat" Habsburg III Holy Roman Emperor was born to Ernest "The Iron" Habsburg I Duke Austria (age 38) and Cymburgis Masovia Duchess Austria (age 21).
On 21 Sep 1417 Walter Tailboys 5th Baron Kyme (age 67) died. His son Walter Tailboys 6th Baron Kyme (age 29) succeeded 6th Baron Kyme.
Before 21 Sep 1439 James "Black Knight of Lorn" Stewart (age 44) and Joan Beaufort Queen Consort Scotland (age 35) were married. She the daughter of John Beaufort 1st Marquess Somerset and Dorset and Margaret Holland Duchess Clarence (age 54). She a great granddaughter of King Edward III of England. 
On 21 Sep 1480 Eleanor Poynings Countess Northumberland (age 58) died at Raby Castle [Map]. Her son Henry Percy 4th Earl of Northumberland (age 31) succeeded 6th Baron Poynings 1C 1337.
On 21 Sep 1516 Matthew Stewart 4th Earl Lennox was born to John Stewart 3rd Earl Lennox (age 26) and Isabel or Elizabeth Stewart Countess Lennox (age 21) at Dumbarton Castle, Dunbarton.
On 21 Sep 1523 Maurice Berkeley 4th Baron Berkeley (age 56) died. His brother Thomas Berkeley 5th Baron Berkeley (age 51) succeeded 5th Baron Berkeley 2C 1421. Eleanor Constable Baroness Berkeley by marriage Baroness Berkeley.
On 21 Sep 1532 William Preston 2nd Viscount Gormanston died. His son Jenico Preston 3rd Viscount Gormanston (age 30) succeeded 2nd Viscount Gormanston, 5th Baron Gormanston.
On 21 Sep 1538 George Tailboys 9th Baron Kyme (age 71) died. He was buried at Lincoln Cathedral [Map]. His grandson George Tailboys 2nd Baron Tailboys 10th Baron Kyme (age 15) de jure 10th Baron Kyme.
George Tailboys 9th Baron Kyme: In 1467 he was born to Robert Tailboys 8th Baron Kyme (age 17) and Elizabeth Heron Baroness Kyme (age 14). In or before 1490 George Tailboys 9th Baron Kyme (age 23) and Elizabeth Gascoigne Baroness Kyme (age 18) were married. Elizabeth Gascoigne Baroness Kyme by marriage Baroness Kyme. They were third cousin once removed. She a great x 4 granddaughter of King Edward III of England. On 30 Jan 1495 Robert Tailboys 8th Baron Kyme (age 45) died. His son George Tailboys 9th Baron Kyme (age 28) de jure 9th Baron Kyme. In 1509 George Tailboys 9th Baron Kyme (age 42) was Keeper of at Harbottle Castle. In Mar 1517 George Tailboys 9th Baron Kyme (age 50) became insane and placed under the care of Cardinal Thomas Wolsey (age 44).
George Tailboys 2nd Baron Tailboys 10th Baron Kyme: Around 1523 he was born to Gilbert Tailboys 1st Baron Tailboys (age 25) and Elizabeth "Bessie" Blount Baroness Clinton and Tailboys (age 25). On 30 Apr 1530 Gilbert Tailboys 1st Baron Tailboys (age 32) died. He was buried at Church of St Mary and All Saints, South Kyme. His son George Tailboys 2nd Baron Tailboys 10th Baron Kyme (age 7) succeeded 2nd Baron Tailboys of Kyme. After 30 Apr 1530 George Tailboys 2nd Baron Tailboys 10th Baron Kyme (age 7) wardship granted to William Fitzwilliam 1st Earl of Southampton (age 40). After 15 May 1539 George Tailboys 2nd Baron Tailboys 10th Baron Kyme (age 16) and Margaret Skipwith Baroness Tailboys were married. She by marriage Baroness Tailboys of Kyme. On 13 Dec 1539 Anne of Cleves (age 24) arrived at Calais. She was met by George Tailboys 2nd Baron Tailboys 10th Baron Kyme (age 16), Thomas Seymour 1st Baron Seymour (age 31) and William Fitzwilliam 1st Earl of Southampton (age 49). Around 06 Sep 1540 George Tailboys 2nd Baron Tailboys 10th Baron Kyme (age 17) died. His brother Robert Tailboys 3rd Baron Tailboys 11th Baron Kyme (age 12) succeeded 3rd Baron Tailboys of Kyme, de jure 11th Baron Kyme.
On 21 Sep 1538 Lewis Mordaunt 3rd Baron Mordaunt was born to John Mordaunt 2nd Baron Mordaunt (age 30) and Ellen Fitzlewis (age 16).
Wriothesley's Chronicle. And the morrow, being Sainct Matthewes daie, all the parishe churches within the citie and the suburbes of the same, kept a solempne procession on their knees in English, with Te Deum after for the said victorie.
In or before 21 Sep 1553 John Dudley 3rd Baron Dudley (age 59) died. His son Edward Dudley 4th Baron Dudley (age 28) succeeded 4th Baron Sutton of Dudley 1C 1440.
On 21 Sep 1558 Charles V Holy Roman Emperor (age 58) died at the Monastery of Yuste. His son Philip "The Prudent" II King Spain (age 31) succeeded II King Spain.
On 21 Sep 1578 Robert Dudley 1st Earl of Leicester (age 46) and Lettice Knollys Countess Essex (age 34) were married secretly much to the anguish of Queen Elizabeth I of England and Ireland (age 45) who developed a deep hatred of Lettice Knollys Countess Essex (age 34). She by marriage Countess of Leicester. Roger North 2nd Baron North (age 48) was present. He the son of John Dudley 1st Duke Northumberland and Jane Guildford Duchess Northumberland.
On 21 Sep 1585 Edward Montagu 1st Baron Montagu (age 22) and Elizabeth Jeffrey (age 17) were married at Weekley.
On 21 Sep 1586 Robert Gage was executed for his involvement in the Babington Plot.
On 21 Sep 1637 Landgrave William V of Hesse-Kassel (age 35) died. His son Wilhelm "The Just" VI Hesse-Kassel (age 8) succeeded VI Landgrave Hesse Kassel.
On 21 Sep 1640 Philip Bourbon I Duke Orléans was born to Louis XIII King France (age 38) and Anne of Austria Spain Queen Consort France (age 38).
Archaeologia Cambrensis 1820 Page 464. Sept. 21. "The King (age 44) passed through Mountgomeryshyre, and lay that night at Llan Fyllin. The next day, the 22d Sept., the King (age 44) marched from Llan Fyllin by Brithdir, where he dined? and gave proclamation among his souldiers, that they should not plunder any thing in Denbyshire, and thence through Mochnant to Cevn hir Fynydd, and so along the tops of the mountains to Chirk Castle [Map]. The rest of the forces marched to Llan-Silin. The next day after, being Tuesday, the King advanced towards Chester.
On 21 Sep 1676 Robert Grierson 1st Baronet (age 21) and Henrietta Douglas Lady Grierson (age 19) were married at Drumlanrig Castle or Sanquhar Castle. She the sister of William Douglas 1st Duke Queensberry (age 39). She the daughter of James Douglas 2nd Earl Queensberry and Margaret Stewart Countess Queensberry.
On or before 21 Sep 1680 William Eure of Elvet and Kelloe in County Durham (age 72) died. His son Peter Eure (age 25) de jure 15th Baron Scrope of Bolton.
On 21 Sep 1690 Wriothesley Baptist Noel 2nd Earl Gainsborough (age 29) died. His half first cousin Baptist Noel 3rd Earl Gainsborough (age 6) succeeded 3rd Earl Gainsborough 1C 1682, 6th Viscount Campden.
On 21 Sep 1691 John Lyon 4th Earl Strathmore and Kinghorne (age 28) and Elizabeth Stanhope Countess Strathmore and Kinghorne (age 28) were married. She the daughter of Philip Stanhope 2nd Earl Chesterfield (age 57) and Elizabeth Butler Countess Chesterfield. He the son of Patrick Lyon 3rd Earl Strathmore and Kinghorne (age 48) and Helen Middleton Countess Strathmore and Kinghorne (age 46).
On 21 Sep 1701 George Byng 3rd Viscount Torrington was born to George Byng 1st Viscount Torrington (age 38).
On 21 Sep 1725 Brownlow Cecil 9th Earl Exeter was born to Brownlow Cecil 8th Earl Exeter (age 24).
On 21 Sep 1744 William Neville 16th and 14th Baron Bergavenny (age 49) died at Bath [Map]. On 30 Sep 1744 he was buried at East Grinstead. His son George Neville 1st Earl Abergavenny (age 17) succeeded 17th Baron Bergavenny 1C 1392, 15th Baron Bergavenny 2C 1450.
On 21 Sep 1745 the army of Charles Edward "Bonnie Prince Charlie" Stewart (age 24) defeated the only government army in Scotland at the Battle of Prestonpans, led by General Sir John Cope (age 57).
Colonel James Gardiner (age 57) was killed in action. He was mortally wounded by the Highlanders after his dragoons had fled the field and he was attempting to rally some foot soldiers. He received a mortal blow whilst wounded on the ground and was stripped to the waist as his possessions were looted by the Highlanders. After the battle he was carried from the field by a servant to nearby Tranent where he soon died.
On 21 Sep 1756 Robert Shirley 7th Earl Ferrers was born to Robert Shirley 6th Earl Ferrers (age 33) and Catherine Cotton Countess Ferrers.
On 21 Sep 1761 John Bentley Ashley (age 59) died. Monument to John Bentley Ashley (age 59) in Saint Leodegarius Church, Ashby St Ledgers [Map]. Sculpted by John "The Elder" Bacon (age 20). Standing wall monument with two large allegorical figures flanking the inscription. Above them is a Sarcophagus on which is a Roman lamp on front of a black Obelisk. Also to James Ashley -1798. Simple Wall Monument with Urn and Obelisk. Also to Jane Pocock (age 51) and by whose will the. Monument was erected.
John Bentley Ashley: He and Jane Pocock were married. Around 1702 he was born to Joseph Ashley of Great Broughton.
Jane Pocock: In 1710 she was born. On 13 Jun 1784 Jane Pocock (age 74) died.
On 21 Sep 1803 William Trench 3rd Earl of Clancarty was born to Richard Le Poer Trench 2nd Earl Clancarty (age 36) and Henrietta Margaret Staples Countess Clancarty (age 33).
On 21 Sep 1803 Thomas Vesey 3rd Viscount Vesci was born to John Vesey 2nd Viscount Vesci (age 32) and Frances Letitia Brownlow Viscountess Vesci.
On 21 Sep 1810 Thomas Bruce 11th Earl Kincardine 7th Earl Elgin (age 44) and Elizabeth Oswald Countess Kincardine and Elgin (age 20) were married. The difference in their ages was 23 years. He the son of Charles Bruce 9th Earl Kincardine 5th Earl Elgin.
On 21 Sep 1817 Jules 1st Duke of Polignac (age 71) died.
On 21 Sep 1821 Edward Chichester 4th Marquess Donegal (age 22) and Amelia Ogrady Marchioness County Donegal were married. He the son of George Chichester 2nd Marquess Donegal (age 52).
On 21 Sep 1845 Ernest Augustus Hanover 3rd Duke Cumberland and Teviotdale was born to George V King Hanover (age 26) and Marie Saxe Altenburg Queen Consort Hanover. He a great grandson of King George III of Great Britain and Ireland.
On 21 Sep 1846 John Upton 2nd Baron Templetown (age 74) died.
On 21 Sep 1848 George Frederick Cavendish-Scott-Bentinck (age 46) died unmarried. He had left his father's home Welbeck Abbey [Map] intending to walk the six miles to Thoresby Hall to dine with Charles Herbert Pierrepont 2nd Earl Manvers (age 70). When he didn't arrive at Thoresby Hall a search party was sent to look for him. They discovered his body at nine in the evening. He was buried in the family vault at St Marylebone Church.
On 21 Sep 1885 Wyndham Knatchbull-Hugessen 3rd Baron Brabourne was born to Edward Knatchbull-Hugessen 2nd Baron Brabourne (age 28) and Amy Virginia Beaumont (age 26).
On 21 Sep 1897 Charles Andrew Vanneck 3rd Baron Huntingfield (age 79) died. His son Joshua Charles Vanneck 4th Baron Huntingfield (age 55) succeeded 4th Baron Huntingfield of Heveningham Hall in Suffolk, 6th Baronet Vanneck of Putney.
On 21 Sep 1909 Edward Guiness 1st Earl Iveagh (age 61) and Adelaide "Dodo" Guinness Countess Iveagh (age 65) were married. They were half third cousins.
On 21 Sep 1909 Edward Frederick Lindley Wood 1st Earl Halifax (age 28) and Dorothy Evelyn Augusta Onslow Countess Halifax (age 24) were married. She the daughter of William Onslow 4th Earl Onslow (age 56) and Florence Coulston Gardner Countess Onslow (age 56).
On 21 Sep 1943 Seymour Bathurst 7th Earl Bathurst (age 79) died. His grandson Henry Allen John Bathurst 8th Earl Bathurst (age 16) succeeded 8th Earl Bathurst of Bathurst in Sussex.
On 21 Sep 1955 Ralph Cockayne Assheton 1st Baronet (age 95) died. His son Ralph Assheton 1st Baron Clitheroe (age 54) succeeded 2nd Baronet Assheton of Downham in Lancaster.
On 21 Sep 1957 Haakon VII King Norway (age 85) died. His son Olav Glücksburg V King Norway (age 54) succeeded V King Norway.
On 21 Sep 1971 Simon Nelson 10th Earl Nelson was born to Peter Nelson 9th Earl Nelson (age 29).
On 21 Sep 1981 George Nelson 8th Earl Nelson (age 76) died. His nephew Peter Nelson 9th Earl Nelson (age 39) succeeded 9th Earl Nelson of Trafalgar and Merson in Surrey, 9th Viscount Merton.
On 21 Sep 2000 John Sutherland Egerton 6th Duke Sutherland (age 85) died. His first cousin once removed Francis Egerton 7th Duke Sutherland (age 60) succeeded 7th Duke Sutherland, 7th Marquess Stafford, 6th Earl Ellesmere, 8th Earl Gower, 10th Baron Gower, 14th Baronet Gower of Stittenham in Yorkshire.