Edward II was the youngest of at least fourteen and perhaps even fifteen or more children, and also had three much younger half-siblings from his father's second marriage to Marguerite of France. Only eight of his father's seventeen or more children survived into adulthood, six from his first marriage and two from his second; I've bolded their names in the post. Edward II was the youngest child of Eleanor of Castile, and although some modern books continue to claim that he had younger sisters Beatrice and Blanche, born in 1286 and 1290, who died young, they didn't exist, and are simply an invention of later genealogists. For centuries, writers have hopelessly, utterly confused the children of Edward I and Eleanor of Castile, given them children they didn't have (such as Juliana and Alice, who is based solely on a misreading on the name of their son Alfonso as mangled by thirteenth-century English scribes), missed children they did have, messed up their dates of birth and death (the eldest surviving daughter Eleanor was born in 1269, not 1264, as numerous modern books and websites still claim; their daughter Margaret was born in March 1275, not September 1275, and died sometime after March 1333, not in 1318, and so on). Eleanor of Castile's biographer John Carmi Parsons has done great work sorting out Eleanor's children; if you're interested in the topic, you really need to get hold of his article 'The Year of Eleanor of Castile's Birth and her Children by Edward I', Mediaeval Studies, 46 (1984), on which this post is based.
- (Daughter, born and died in May 1255?). Not entirely clear, but evidence indicates that Eleanor of Castile bore a daughter, name unknown, who died on 29 May in an unknown year and was buried in Bordeaux. 1255 is the year which makes most sense, according to Parsons, less than seven months after Eleanor married and when she was still only about thirteen and a half.
- Katherine, born c. 1261/63, died September 1264.
- Joan, born January 1265, died September 1265.
- John, born July 1266, died August 1271. Edward I's eldest son, never heir to the throne as he died in the lifetime of his grandfather Henry III, left in the care of his great-uncle Richard of Cornwall (Henry's brother) when his father went on crusade to the Holy Land in 1270, and died at Richard's castle of Wallingford. Named after his great-grandfather King John, presumably.
- Henry, born May 1268, died October 1274. Named after his grandfather Henry III. Heir to the English throne from the accession of his father in November 1272 until his death at Guildford aged six two years later.
- Eleanor, born June 1269, died August 1298; two children, Edouard I, count of Bar, c. 1294/95-1336, and Joan, countess of Surrey, c. 1295/96-1361.
The fifth or sixth child of Edward I and Eleanor of Castile and the eldest to survive. Born shortly before 18 June 1269, as an entry on the Patent Roll makes clear. Often wrongly stated to have been born in 1264, which is an error based on a misunderstanding of the word primogenita to describe her. Although this literally means 'first born daughter', it was used in the sense of 'eldest surviving daughter': Edward II's queen Isabella was called the primogenita of Philip IV of France despite having two older sisters who died young, and Edward's brother Alfonso of Bayonne was also often called Edward I's primogenitus during the ten years (1274-1284) he was heir to the English throne, though he certainly had two older brothers, John and Henry. Eleanor is thus frequently confused with her sister Katherine, who died in 1264, and this is often wrongly given as Eleanor's birth year. Eleanor was betrothed in June 1282 to Alfonso III of Aragon, who was born in 1265 and died suddenly in June 1291. In September 1293 when she was twenty-four, she married Henri III, count of Bar in eastern France, and died when she was twenty-nine.
- Daughter, name unknown, born in Acre in the Holy Land in 1271 and died there.
- Joan of Acre, born sometime in 1272 in Acre; died April 1307. She married the much older Gilbert 'the Red' de Clare, earl of Gloucester and had four children, and secondly the squire Ralph de Monthermer, and had four more children with him. Joan died a few weeks before her father. Her children included Gilbert, earl of Gloucester, Margaret, countess of Cornwall and Gloucester, and Mary, countess of Fife.
- Alfonso, born in Bayonne in November 1273, died August 1284. Named after his uncle and godfather Alfonso X of Castile, and heir to the English throne from the death of his brother Henry when he was eleven months old until his own death just under ten years later. Died while negotiations were going ahead for his marriage to Count Floris V of Holland's daughter Margaret.
- Margaret, born March 1275, died after March 1333. Margaret married the future Duke John II of Brabant in July 1290, and they had one child born in 1300, Duke John III. It is still often stated even today that Margaret died in 1318, which baffles me, as she was in occasional contact with her brother Edward II in the 1320s and with her nephew Edward III in 1333. The date of her death is unrecorded.
- Berengaria, born May 1276, died June 1278. Named presumably after Eleanor of Castile's paternal grandmother Berenguela or Berengaria (1180-1246), queen of Castile in her own right.
- Daughter, name unknown, born and died January 1278.
- Mary, born March 1279, died May 1332. A reluctant nun at Amesbury Priory.
- Elizabeth of Rhuddlan, born August 1282, died May 1316. Married firstly John I, count of Holland, who died childless aged fifteen in 1299, and secondly Humphrey de Bohun, earl of Hereford and Essex. She had ten children, six of whom lived into adulthood: Eleanor, countess of Ormond; John, earl of Hereford; Humphrey, earl of Hereford; Margaret, countess of Devon; Edward; William, earl of Northampton.
- Edward of Caernarfon, born 25 April 1284, King Edward II of England 8 July 1307 to 24 January 1327. My boy. :-) Eleanor of Castile's youngest child; she was about forty-two and a half at the time of his birth. Edward became heir to the throne at just under four months old, on the death of his brother Alfonso of Bayonne on 19 August 1284.
- Thomas of Brotherton, earl of Norfolk, born June 1300, died August 1338. Eldest child of Edward I and his second queen Marguerite of France, made earl of Norfolk in 1312. He and his wife Alice Hales had three children, and his heir was his eldest child, Margaret.
- Edmund of Woodstock, earl of Kent, born August 1301, executed March 1330. Second son of Edward I and Marguerite. He married Margaret Wake in 1325 and had four children, and his ultimate heir was his second daughter Joan, mother of Richard II.
- Eleanor, born May, 1306, died August 1311. Youngest child of Edward I and born when he was nearly sixty-seven. She died aged five and was buried at Beaulieu Abbey by her half-brother Edward II.
So there we have it. Edward II had at least ten, maybe eleven older sisters, of whom five (Eleanor, Joan, Margaret, Mary and Elizabeth) lived into adulthood, and a half-sister young enough to be his daughter (twenty-two years' age difference), who died when she was five. He had three older brothers who died when they were five, six and ten, and two much younger half-brothers, who survived childhood. When Edward succeeded to the throne at the age of twenty-three on 7 July 1307, only three of his older sisters and his little half-sister were still alive, and only Margaret and Mary were still alive at the time of his deposition in January 1327. Of his younger half-brothers, Edmund was executed at twenty-eight, and Thomas died of natural causes at thirty-eight. Apart from Margaret and Mary (and possibly Edward II, if we assume that he wasn't murdered in 1327), who lived into their fifties, the children of Edward I were not a long-lived lot. Assuming that there really was a daughter born in 1255 a few months after his wedding, this means that Edward I fathered children for a period of over fifty years, 1255-1306.