Philippa, 5th Countess of Ulster

Philippa of Clarence (16 August 1355 – 5 January 1382) was a medieval English princess and 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. She was the eldest grandchild of King Edward and Queen Philippa, her namesake. 
Philippa married Edmund Mortimer, 3rd Earl of March, at the age of about 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 Richard of Conisburgh, 3rd Earl of Cambridge, a son of Edmund of Langley, 1st Duke of York.
Philippa died in 1382 and was buried at Wigmore Abbey, Herefordshire.
Marriage and issue.
Her children with Edmund Mortimer were as follows:
And one other child, John de Mortimer (c. 1378–1424), Knight.