World of HYDE
Discovering our Ancestors and their descendants to all parts of the world. Last updated 5th September 2025
Lady Philippa Plantagenet, 5th Countess Of Ulster[1]
1355 - 1382 (26 years)
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Name Philippa Plantagenet Prefix Lady Suffix 5th Countess Of Ulster Birth 16 Aug 1355 Eltham Palace, Kent, England 
Gender Female _AMTID 192683667652:1030:204653251 _COLOR 15 _FSFTID LCM6-WCL _UID 8920B01B665F417785A77CAAA648AD9A785C Death 5 Jan 1382 Cork, Cork, Ireland Burial Aft 5 Jan 1382 Wigmore Abbey, Wigmore, Herefordshire, England Person ID I17944 World of Hyde Last Modified 9 Apr 2025
Father Lionel Plantagenet, Of Antwerp 1st Duke Of Clarence, b. 29 Nov 1338, Antwerp, Flemish Brabant, Belgium d. 17 Oct 1368, Alba, Provincia di Cuneo, Piemonte, Italy (Age 29 years) Mother Lady Elizabeth De Burgh, Duchess Of Clarence 4th Countess Of Ulster, b. 6 Jul 1332, Carrickfergus Castle, County Antrim, Ireland d. 10 Dec 1363, Baile Átha Cliath, Dublin, Ireland, United Kingdom (Age 31 years) Marriage 15 Aug 1352 Tower of London Family ID F16629 Group Sheet | Family Chart
Family Edmund De Mortimer, 3rd Earl Of March, b. 1 Feb 1352, Llyswen, Breconshire, Wales d. 27 Dec 1381, Cork, Ireland (Age 29 years) Marriage May 1368 Reading, Berkshire, England Address:
Queen's ChapelChildren 1. Lady Elizabeth De Mortimer, b. 12 Feb 1371, Usk, Monmouthshire, Wales d. 20 Apr 1417, Trotton, Sussex, England (Age 46 years)2. Lady Agnes Mortimer, b. 1372, Reading, Berkshire, England, United Kingdom d. 20 Apr 1417, Of, Yorkshire, England (Age 45 years)3. Joanne Mortimer, b. 1365, Ludlow Castle, Shropshire, England d. 8 Oct 1405, Wiltshire, England (Age 40 years)4. Roger Mortimer, 4th Earl Of March, b. 11 Apr 1374 d. 20 Jul 1398 (Age 24 years) Family ID F5210 Group Sheet | Family Chart Last Modified 5 Sep 2025
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Event Map 
Marriage - Address:
Queen's Chapel - May 1368 - Reading, Berkshire, England
Death - 5 Jan 1382 - Cork, Cork, Ireland = Link to Google Earth
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Photos 
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Notes - Philippa of Clarence (16 August 1355-5 January 1382) was the suo jure Countess of Ulster.
Biography
She was born at Eltham Palace in Kent on 16 August 1355, the only child of Lionel of Antwerp, 1st Duke of Clarence, and Elizabeth de Burgh, 4th Countess of Ulster. Her father was the third son, but second son to survive infancy, of King Edward III of England and Philippa of Hainault.
Philippa married Edmund Mortimer, 3rd Earl of March, in 1368 at the age of thirteen in the Queen's Chapel at Reading Abbey, an alliance that would have far-reaching consequences in English history. Her cousin, King Richard II, remained childless, making Philippa and her descendants next in line to the throne until his deposition. In the Wars of the Roses, the Yorkist claim to the crown was based on descent from Edward III through Philippa, her son Roger Mortimer, and granddaughter Anne Mortimer, who married a son of the 1st Duke of York.
Philippa died in 1378, and was buried at Wigmore Abbey, Herefordshire.
Marriage and issue
1.) Lady Elizabeth Mortimer, 12 February 1371-20 April 1417, She first married Sir Henry 'Hotspur' Percy, with whom she had two children, Henry Percy, 2nd Earl of Northumberland, and Lady Elizabeth Percy. Her second husband was Thomas de Camoys, Baron Camoys, with whom she had a son, Lord Roger de Camoys.
Elizabeth Mortimer was an ancestor of the third Queen Consort of Henry VIII, Jane Seymour.
2.) Roger Mortimer, 4th Earl of March, 11 April 1374-20 July 1398, He married Lady Alianore Holland, by whom he had four children, Anne, Edmund, 5th Earl of March, Eleanor, and Roger. The House of York's claim to the throne was through his eldest daughter, Anne Mortimer.
3.) Lady Philippa Mortimer, 21 November 1375-26 September 1400. She first married John Hastings, 3rd Earl of Pembroke. Her second husband was Richard Fitzalan, 11th Earl of Arundel, with whom she had a son, John, who died young. Her third husband was Sir Thomas Poynings of Basing, 5th Baron St. John.
4.) Sir Edmund Mortimer, 9 November 1376-13 May 1411. Married Catrin (Catherine) Glyndwr, the daughter of Owain Glyndwr. They had issue, possibly a son named Lionel, said to have died young, and three daughters who died in the Tower of London alongside their mother.
- Philippa of Clarence (16 August 1355-5 January 1382) was the suo jure Countess of Ulster.
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Sources - [S3] Geni World Family Tree, https://www.myheritage.com/research/record-40000-3371044/philippa-of-clarence-5th-countess-of-ulster-in-geni-world-family-tree.
Philippa of Clarence, 5th Countess of Ulster Gender: Female Alias name: Countess of Ulster Birth: Aug 16 1355 - Eltham Palace, Kent, England Marriage: Spouse: Edmund "The Good" de Mortimer, 3rd Earl of March - Circa May 1368 Death: Jan 5 1382 - Cork, Ireland Burial: Wigmore Abbey, Wigmore, Herefordshire, England Father: Lionel of Antwerp, 1st Duke of Clarence Mother: Elizabeth de Burgh, 4th Countess of Ulster Husband: Edmund "The Good" de Mortimer, 3rd Earl of March Children: Elizabeth Percy (born Mortimer), Agnes King (born Mortimer), Roger de Mortimer, 4th Earl of March, Philippa Poynings (born de Mortimer), George Mortimer, Edmund Mortimer, Joan Mortimer, Anne Mortimer, John Mortimer
- [S3] Geni World Family Tree, https://www.myheritage.com/research/record-40000-3371044/philippa-of-clarence-5th-countess-of-ulster-in-geni-world-family-tree.