Isabella of Castile, the Controversial First Duchess of York, c.1355-1392

Isabella of Castile

As the third daughter of Peter the Cruel of Castile and his long-term mistress (and sometime wife) Maria of Padilla, Isabella of Castile‘s childhood was marred by her father’s battles to hold on to his throne and almost constant warfare with Aragon.

Peter was known in some areas as Peter the Cruel and in others as Peter the Just, depending which side of the conflict people were on. He received support from Edward III of England’s eldest son and heir Edward, the Black Prince, but Peter’s failure to pay the costs of the prince’s campaign,  his faithlessness, and the failing health of the Black Prince, meant the king of Castile was left to his own devices by 1367. Adding to Peter’s woes, his own nobles backed the king’s illegitimate brother, Henry of Tastamara, as an alternative candidate. Henry eventually defeated and killed Peter in March 1369.

Isabella’s mother had died in 1361 and her 3-year-old brother, Alfonso, in 1362. On Peter’s death, Isabella’s older sister, Constance, inherited their father’s claim to the crown of Castile, but was unable to pursue this claim. This situation in Castile was precarious, to say the least. Taking Isabella with her, the two princesses took refuge in the English territory of Guyenne. The English took the princesses in and soon after, in September 1371, Constance was married to John of Gaunt, the third surviving son of Edward III, at Roquefort. John of Gaunt had become duke of Lancaster on marrying his first wife, Blanche of Lancaster, who had died in 1368; saw this second marriage as an opportunity to gain a kingdom of his own. When the newly married couple returned to London, they brought Constance’s sister, Isabella, with them.


Following Constance’s official entry into London, Isabella married John’s younger brother, Edmund of Langley, the fifth son of Edward III, on 11 July 1372, at Wallingford. In marrying Isabella, Edmund was likely following his father’s instructions, in pursuit of the English policy of the time, to reinforce the dynastic link between England and Castile and thus ensuring that both heirs of Peter of Castile were married into the English royal line. On her marriage to Edmund, Isabella became Countess of Cambridge, and would become the first ever Duchess of York when Edmund was created Duke of York by his nephew, King Richard II, on 6 August 1385. She was appointed a Lady of the Garter in 1379.

The couple’s first son, Edward was born the following year – he would become the second Duke of York, and be killed at Agincourt in 1415. A daughter, Constance, was born in 1374.

Chroniclers of the time reported that Isabella and Edmund were an ill-matched pair; Thomas of Walsingham, in particular, commented on Isabella’s ‘loose morals’, probably referring to her not-so-secret affair with John Holland, Duke of Exeter and half-brother to the king, Richard II. The affair is believed to have started as early as 1374 and has cast doubt on the legitimacy of Edmund and Isabella’s third and youngest child, Richard of Conisbrough. Richard, grandfather of both Edward IV and Richard III, was born at Conisbrough Castle in Yorkshire, sometime between 1375 and 1386. He was executed for his involvement in the Southampton Plot, against Henry V, in 1415.

Conisbrough Castle, Yorkshire

Isabella died on 23rd December 1392, aged about 37, and was buried at the church of the Dominicans, in King’s Langley, on 14 January 1393. In her will, she made Richard II her heir and asked that he provide a pension for her youngest son and Richard II’s godson, Richard of Conisbrough. Richard was given an allowance of £500 by the king, but this was only paid sporadically following Richard II’s deposition by Henry IV.

Richard was not even mentioned in the wills of his father and brother and G.L. Harriss, of the Oxford Dictionary of National Biography, has speculated this could be proof that Richard was not the son of the Duke of York.

Edmund married again, to his cousin Joan Holland, niece of his first wife’s lover, John Holland. In another bizarre family twist, it was Joan’s brother, Edmund Holland, 4th Earl of Kent, who had an affair – and an illegitimate daughter – with Constance of York, the daughter of Edmund and Isabella.


Sources: Ian Mortimer, Edward III The Perfect King;;; History Today Companion to British History; WM Ormrod, The Reign of Edward III; Conisbrough Castle, South Yorkshire;

Photos from Wikipedia, except Conisbrough Castle which is © Sharon Bennett Connolly.


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©2015 Sharon Bennett Connolly

43 thoughts on “Isabella of Castile, the Controversial First Duchess of York, c.1355-1392

  1. James 08/01/2015 / 16:07

    I really enjoyed this, Sharon.

    Thanks for sharing!


  2. Gloria 08/01/2015 / 19:24

    Interesting. Must have been risky behavior on her part. Maybe linked to the DNA issue now revealed by RIII’s remains.

    Liked by 2 people

    • Sharon Bennett Connolly 08/01/2015 / 19:37

      I think you’re right, Gloria. There is a distinct possibilty that this is where the break in DNA occurred. It would certainly make sense. And it wouldn’t mean that Richard III and Edward IV’s claims to the throne were invalid, as their superior claim was through Richard of Conisbrough’s wife, Anne Mortimer, via her descent from Lionel of Antwerp, rather than Richard of Conisbrough himself.

      Liked by 2 people

  3. karrrie49 09/01/2015 / 12:22

    Really interesting blog Sharon… What a life and the issue of DNA break here is interesting. Thanks hope you will do more will reblog it.


  4. karrrie49 09/01/2015 / 12:24

    Reblogged this on karenstoneblog and commented:
    Really interesting piece on Isabella of Castile the first Duchess of York


  5. Bernadette 09/01/2015 / 12:27

    Hi Sharon, Isabella sounds very interesting. Looking forward to the next article xx


  6. thefemalescriblerian 09/01/2015 / 16:13

    Really interesting. Funny to think of the links between England and Spain existing a long time before the more famous Catherine of Aragon made an appearance in the history books!

    Liked by 2 people

  7. hever1536 08/01/2016 / 17:21

    Really enjoyed this article, very interesting!


  8. kristinaaldrup 23/12/2018 / 16:41

    As I read… there was a breathless quality… waiting for the next event. Especially since John of Ghent is an Ancestor.


  9. Linda 24/12/2020 / 10:51

    I am listening to Ian Mortimer’s The perfect King at the moment it is very good ,thanks for the insight to Isabella. Merry Christmas x


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