Mary of Lancaster, Baroness Percy (1320 – 1 September 1362), was the youngest surviving child of Henry, 3rd Earl of Lancaster

Henry, 3rd Earl of Lancaster

Henry , 3rd Earl of Leicester and Lancaster was an English nobleman, one of the principals behind the deposition of Edward II of England.-Family and lineage:...

 by his wife Maud Chaworth

Maud Chaworth

Maud de Chaworth was an English noblewoman and wealthy heiress. She was the only child of Patrick de Chaworth. Sometime before 2 March 1297, she married Henry, 3rd Earl of Lancaster, by whom she had seven children...

. Through her father, she was a great-granddaughter of Henry III of England

Henry III of England

Henry III was the son and successor of John as King of England, reigning for 56 years from 1216 until his death. His contemporaries knew him as Henry of Winchester. He was the first child king in England since the reign of Æthelred the Unready...

.

Family

Mary was a sister of Henry of Grosmont, 1st Duke of Lancaster

Henry of Grosmont, 1st Duke of Lancaster

Henry of Grosmont, 1st Duke of Lancaster, 4th Earl of Leicester and Lancaster, KG , also Earl of Derby, was a member of the English nobility in the 14th century, and a prominent English diplomat, politician, and soldier...

, Maud, Countess of Ulster, Joan, Baroness de Mowbray

Joan of Lancaster

Joan of Lancaster sometimes called Joan Plantagenet after her dynasty's name, was the third daughter of Henry, 3rd Earl of Lancaster and Maud Chaworth.-Marriage:...

, and Eleanor, Countess of Arundel

Eleanor of Lancaster

Eleanor of Lancaster, Countess of Arundel was the fifth daughter of Henry, 3rd Earl of Lancaster and Maud Chaworth.-First marriage and issue:...

. Through her brother Henry, she was the aunt of Blanche of Lancaster

Blanche of Lancaster

Blanche of Lancaster, Duchess of Lancaster was an English noblewoman and heiress, daughter of England's wealthiest and most powerful peer, Henry of Grosmont, 1st Duke of Lancaster...

, first wife of John of Gaunt

John of Gaunt, 1st Duke of Lancaster

John of Gaunt, 1st Duke of Lancaster , KG was a member of the House of Plantagenet, the third surviving son of King Edward III of England and Philippa of Hainault...

 and mother of Henry IV of England

Henry IV of England

Henry IV was King of England and Lord of Ireland . He was the ninth King of England of the House of Plantagenet and also asserted his grandfather's claim to the title King of France. He was born at Bolingbroke Castle in Lincolnshire, hence his other name, Henry Bolingbroke...

.

Marriage

In September or before, 1334 at Tutbury Castle

Tutbury Castle

Tutbury Castle is a largely ruinous medieval castle at Tutbury, Staffordshire, England, in the ownership of the Duchy of Lancaster. It is a Grade I listed building...

, she married Henry Percy, eldest son of Henry Percy, 2nd Baron Percy and Idoine de Clifford. He succeeded his father as 3rd Baron Percy in 1352, making her known as Baroness Percy until her death.

They had the following surviving issue:

• Henry Percy, 1st Earl of Northumberland
  Henry Percy, 1st Earl of Northumberland
  Henry Percy, 1st Earl of Northumberland, 4th Baron Percy, titular King of Mann, KG, Lord Marshal was the son of Henry de Percy, 3rd Baron Percy and a descendent of Henry III of England. His mother was Mary of Lancaster, daughter of Henry, 3rd Earl of Lancaster, son of Edmund, Earl of Leicester and...
  
   (10 November 1341-20 February 1408) married firstly Margaret Neville and secondly Maud, Baroness Lucy.
• Thomas Percy, 1st Earl of Worcester
  Thomas Percy, 1st Earl of Worcester
  Thomas Percy, 1st Earl of Worcester, KG was an English medieval nobleman best known for taking part in the rebellion with his nephew Henry Percy, known as 'Harry Hotspur', and brother Northumberland .-Lineage:...
  
   (1344–1403).
• Maud Percy, married Sir John de Southeray, illegitimate son of King Edward III
  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 his mistress Alice Perrers
  Alice Perrers
  Alice Perrers was a royal mistress whose lover and patron was King Edward III of England. She acquired significant land holdings. She served as a lady-in-waiting to Edward's consort, Philippa of Hainault.-Life and Family:...
  
  .
• Mary, Baroness Ros (born 1360) married John, Baron Ros of Helmsley.

Death

Mary died at Alnwick, Northumberland, England on 1 September 1362, where she was also buried. Her husband Henry would marry a second time to Joan Orreby, daughter and heiress of John, 2nd Lord Orreby.

Ancestry