Philippa of Clarence was the Countess of Ulster

Ulster

Ulster is one of the four provinces of Ireland, located in the north of the island. In ancient Ireland, it was one of the fifths ruled by a "king of over-kings" . Following the Norman invasion of Ireland, the ancient kingdoms were shired into a number of counties for administrative and judicial...

 suo jure

Suo jure

Suo jure is a Latin phrase meaning "in her [or his] own right".It is commonly encountered in the context of titles of nobility, especially in cases where a wife may hold a title in her own right rather than through her marriage....

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Philippa was born in Eltham Palace

Eltham Palace

Eltham Palace is a large house in Eltham, within the London Borough of Greenwich, South East London, England. It is an unoccupied royal residence and owned by the Crown Estate. In 1995 its management was handed over to English Heritage which restored the building in 1999 and opened it to the public...

, Kent

Kent

Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 on 16 August 1355. She was the daughter and only child of Lionel of Antwerp, 1st Duke of Clarence

Lionel of Antwerp, 1st Duke of Clarence

Lionel of Antwerp, 1st Duke of Clarence, jure uxoris 4th Earl of Ulster and 5th Baron of Connaught, KG was the third son, but the second son to survive infancy, of Edward III of England and Philippa of Hainault...

 and Elizabeth de Burgh, 4th Countess of Ulster

Elizabeth de Burgh, 4th Countess of Ulster

Elizabeth de Burgh, Duchess of Clarence, suo jure 4th Countess of Ulster and 5th Baroness of Connaught was a Norman-Irish noblewoman who married Lionel of Antwerp, 1st Duke of Clarence.- Family :...

. Her father was the second son of King Edward III of England

Edward III of England

Edward III was King of England from 1327 until his death and is noted for his military success. Restoring royal authority after the disastrous reign of his father, Edward II, Edward III went on to transform the Kingdom of England into one of the most formidable military powers in Europe...

 and Philippa of Hainault

Philippa of Hainault

Philippa of Hainault, or, Philippe de Hainaut was the Queen consort of King Edward III of England. Edward, Duke of Guyenne, her future husband, promised in 1326 to marry her within the following two years...

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Philippa married Edmund Mortimer, 3rd Earl of March in about 1368 at Reading Abbey

Reading Abbey

Reading Abbey is a large, ruined abbey in the centre of the town of Reading, in the English county of Berkshire. It was founded by Henry I in 1121 "for the salvation of my soul, and the souls of King William, my father, and of King William, my brother, and Queen Maud, my wife, and all my ancestors...

, forging an alliance that would have far-reaching consequences in English history. During her own lifetime, Philippa was the heiress presumptive

Heir Presumptive

An heir presumptive or heiress presumptive is the person provisionally scheduled to inherit a throne, peerage, or other hereditary honour, but whose position can be displaced by the birth of an heir or heiress apparent or of a new heir presumptive with a better claim to the position in question...

 to her first cousin Richard II

Richard II of England

Richard II was King of England, a member of the House of Plantagenet and the last of its main-line kings. He ruled from 1377 until he was deposed in 1399. Richard was a son of Edward, the Black Prince, and was born during the reign of his grandfather, Edward III...

, and would be displaced in the succession by any children of the king. After her death in 1382, her rights passed on to her son, Roger Mortimer, 4th Earl of March. When Richard resigned his crown without issue on 29 September 1399, the rightful heir was Edmund Mortimer, 5th Earl of March, whose father Roger had died the previous year. However, the throne was usurped by Richard and Philippa's first cousin, Henry Bolingbroke, an event that later precipitated the Wars of the Roses

Wars of the Roses

The Wars of the Roses were a series of dynastic civil wars for the throne of England fought between supporters of two rival branches of the royal House of Plantagenet: the houses of Lancaster and York...

. As a result of her seniority in the line of succession to the throne of the Kingdom of England

Kingdom of England

The Kingdom of England was, from 927 to 1707, a sovereign state to the northwest of continental Europe. At its height, the Kingdom of England spanned the southern two-thirds of the island of Great Britain and several smaller outlying islands; what today comprises the legal jurisdiction of England...

 and her marriage into the powerful Mortimer family, her descendants eventually succeeded to the throne as the House of York

House of York

The House of York was a branch of the English royal House of Plantagenet, three members of which became English kings in the late 15th century. The House of York was descended in the paternal line from Edmund of Langley, 1st Duke of York, the fourth surviving son of Edward III, but also represented...

 under Edward IV

Edward IV of England

Edward IV was King of England from 4 March 1461 until 3 October 1470, and again from 11 April 1471 until his death. He was the first Yorkist King of England...

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She died, most likely of a fever, on 5 January 1382 in Cork

Cork (city)

Cork is the second largest city in the Republic of Ireland and the island of Ireland's third most populous city. It is the principal city and administrative centre of County Cork and the largest city in the province of Munster. Cork has a population of 119,418, while the addition of the suburban...

, Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

, and was buried in Wigmore, Herefordshire.

Marriage and issue

She had five children by her marriage to Edmund Mortimer:

Name	Birth	Death	Notes
Lady Elizabeth Mortimer Lady Elizabeth Mortimer Elizabeth Mortimer, Baroness Camoys was an English noblewoman, who, as the granddaughter of Lionel of Antwerp, 1st Duke of Clarence, was in the line of succession to the English throne. Her first husband was Sir Henry Percy, known to history as "Hotspur"...	12 February 1371	20 April 1417	She married firstly Henry Percy, with whom she had three children, and secondly Thomas de Camoys Thomas de Camoys, 1st Baron Camoys Thomas de Camoys, 1st Baron Camoys, KG , was an English peer and soldier.De Camoys was the son of Sir John de Camoys. In August 1383 he was summoned to the House of Lords as Lord Camoys. He fought in the Hundred Years' War and commanded the left wing of the English Army at the Battle of Agincourt... , Baron Camoys Baron Camoys Baron Camoys is a title that has been created twice in the Peerage of England, both times by writ. The first creation came in 1264 when Ralph de Camoys was summoned to Parliament as Lord Camoys... , with whom she had a son, Lord Roger de Camoys, and a daughter, Alice, who was in turn, the mother of William Hastings, Baron Hastings. Lady Elizabeth and Henry Percy were ancestors of Queen consort Jane Seymour Jane Seymour Jane Seymour was Queen of England as the third wife of King Henry VIII. She succeeded Anne Boleyn as queen consort following the latter's execution for trumped up charges of high treason, incest and adultery in May 1536. She died of postnatal complications less than two weeks after the birth of...  and her siblings.
Roger Mortimer, 4th Earl of March	11 April 1374	20 July 1398	He married Lady Alianore Holland Alianore Holland Alianore Holland, Countess of March was an English noblewoman, and the wife of Roger Mortimer, 4th Earl of March the heir presumptive of her half-uncle King Richard II of England, and Lord Lieutenant of Ireland. She was the mother of Anne Mortimer, and Edmund Mortimer, 5th Earl of March... , by whom he had five children. The House of York's claim to the throne was through his eldest daughter and heir Anne Mortimer.
Lady Philippa Mortimer	21 November 1375	26 September 1400	She married first John Hastings, 3rd Earl of Pembroke John Hastings, 3rd Earl of Pembroke John Hastings, 3rd Earl of Pembroke was the son of John Hastings, 2nd Earl of Pembroke and Anne Manny, 2nd Baroness Manny...  secondly Richard Fitzalan, 11th Earl of Arundel Richard FitzAlan, 11th Earl of Arundel Richard FitzAlan, 11th Earl of Arundel and 9th Earl of Surrey KG was an English medieval nobleman and military commander.-Lineage:...  and had issue a son John, who died young. And thirdly she married Sir Thomas Poynings of Basing.
Sir Edmund Mortimer Edmund Mortimer, son of the 3rd Earl Edmund Mortimer , was the second son of Edmund Mortimer, 3rd Earl of March by his wife Philippa Plantagenet, and is the best-known of the various Edmund Mortimers because of his role in the rebellion of Owain Glyndŵr...	9 November 1376	13 May 1411	Married Catrin (Catherine) Glyndŵr the daughter of Owain Glyndŵr Owain Glyndwr Owain Glyndŵr , or Owain Glyn Dŵr, anglicised by William Shakespeare as Owen Glendower , was a Welsh ruler and the last native Welshman to hold the title Prince of Wales...  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.
Sir John de Mortimer?	c. 1378?	1424?	(An unconfirmed son cited in some sources)

Ancestry