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

Isabella of Castile

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 on allegiances. He received support from Edward III’s son the Black Prince, but his failure to pay the costs of the campaign,  his faithlessness, and the failing health of the black Prince, meant he was left to his own devices by 1367. Peter’s own nobles backed his illegitimate brother, Henry of Tastamara, who 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 her father’s claim to the crown of Castile, but was unable to pursue her claim. Taking Isabella with her, the two princesses took refuge in the English territory of Guyenne. Constance married John of Gaunt (third son of Edward III) at Roquefort in September 1371. Gaunt saw the marriage as an opportunity to gain a kingdom of his own. When the newly married couple returned to London, they brought 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 who would later become the first Duke of York, in 1372. Their 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 somewhere between 1375 and 1386. He was executed for his involvement in the Southampton Plot, against Henry V, in 1415.

Conisbrough Castle, South Yorkshire

Isabella died on 23rd December 1392 and is buried at King’s Langley. 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. 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

41 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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