Because for some reason they've been taking up lots of space rent-free in my head recently, here's a post about the affairs and the many illegitimate children of John de Warenne, earl of Surrey and Sussex. John, born 1286 and died 1347, had an utterly disastrous marriage to Edward II's niece Jeanne de Bar, and it occurs to me now that we should have included the unfortunate countess in Queen Isabella's tragic wives' support group:
Jeanne: My husband had left me for his mistress by the time I was fourteen, and he lived openly with her and ignored me even after he was threatened with excommunication for abandoning his lawful wife, and left my Uncle Edward to take care of me and pay all my living costs. Yes, Izzy, that's the same man as the husband you keep whinging about. John fathered nine children that I know of, some by his long-term mistress Maud Nerford and some by other women but none by me, and spent literally decades trying to get our marriage annulled. The git tried to bribe me with an income of 200 poxy quid a year if I agreed to the annulment. In the end, he was so desperate to get rid of me so he could marry his new mistress, who to add insult to injury was years younger than some of his own children, that he pretended to the pope that he'd had an incestuous affair with my Aunt Mary. Mary wasn't only seven years older than him, she was a nun!
Isabella: Pffft, Jeanie, the Rules For Writing About The Fourteenth Century, section 15, clause 8 ("How to decide if a wife is tragically neglected") clearly state that if your husband cheats on you with women, no matter how blatantly, or how much he humiliates and belittles and ignores you, or how many children he fathers on his numerous mistresses, he's a romantic Hetero Hero and you just have to suck it up. Whereas I, with a husband who prefers men, am entitled to, ooooh, simply tons of sympathy. Don't be glaring at me like that; I didn't make the rules.
John and Jeanne married at Westminster on 25 May 1306, when he was almost twenty and Jeanne probably only ten, and certainly no more than eleven. Evidently sick of waiting for his little wife to grow up, John looked elsewhere, and his biographer F. R. Fairbank commented in 1907 "his wife when they married was a child, and half his own age; it is not wonderful [i.e. not to be wondered at] that the marriage was not a success. He was probably not one whit worse than the great majority in his own station."  Hmmm, a man marrying a girl half his age and having outside interests; does that remind you of anyone?
On 16 August 1309, Edward II gave John licence "to make whom he please heir of the lands which he holds," as long as he "will not disinherit any heir he may have by the king's niece," which suggests that even then, despite her extreme youth, John wasn't sure if he would ever have children with Jeanne and that their marriage was not a success.  John had an illegitimate son called William born sometime before 24 August 1310 (see below), and it may have been his birth or imminent birth which prompted John to ask this favour of the king. In the spring of 1313, John and Jeanne's marriage collapsed completely: Edward sent William Aune to bring Jeanne to him and subsequently paid all her expenses at the Tower of London, and specifically invited her to come with him on his trip to France that year. John meanwhile was openly living with his mistress Maud Nerford and was threatened with excommunication on this account in 1313, a sentence finally carried out three years later. He had at least three sons with Maud, and in 1316 made strenuous though ultimately unsuccessful efforts to annul his marriage to Jeanne, marry Maud and make these boys his heirs. By the autumn of 1320, though, his relationship with Maud had ended: he petitioned parliament to ask for her brother John to be removed from a commission of oyer et terminer in Norfolk on the grounds that John Nerford and his fellow commissioners were doing all the harm they could to John, because he had "banished Maud de Nerford from his heart and ousted her from his company." 
By the end of John's life, he was living with another highborn mistress, Isabel Holland, and was once more attempting to annul his marriage to Jeanne in order to marry Isabel instead. In June 1346, he made an arrangement with Edward III regarding the settlement of his lands which makes it clear that despite his age - he turned sixty that month - he hadn't given up hope of marrying and fathering a legitimate heir by Isabel, who was over thirty years his junior (even her mother was three or four years younger than he was).  In his will of 24 June 1347, John referred to Isabel as ma compaigne, the same way men of the era referred to their wives - but however John might have wished that she was, Isabel wasn't his wife as he never managed to annul his marriage to the childless Jeanne de Bar, and although he fathered lots of children by other women, his heir was his sister Alice's son Richard 'Copped Hat', earl of Arundel. (His Yorkshire lands passed to Edward III's son Edmund of Langley, John's godson.) John completely ignored his wife of forty-one years in his will but left numerous possessions to his mistress Isabel, including all his beds, half his livestock, various gold rings, chapel vestments, a gold cup and a large amount of other valuable plate, and "all the residue of all my goods and chattels" after his bequests and debts had been paid.
John left bequests to three daughters in his will. I don't know the identity of their mother(s):
- Joan de Basing ('Johanne de Basyngg' in the original spelling) who received a cup of plain silver from her father. Judging by her last name, she was already married. Joan was the name of John's mother, which implies Joan de Basing was his eldest daughter, as does the fact that she was named first in the list of his daughters.
- Katherine, who according to several genealogy sites - I don't know what primary source is the basis for this statement, and I can't confirm it - married Sir Robert Heveningham after her father's death. She certainly received a bequest of ten marks (six pounds, sixty-six pence) in John's will. ('Katerine' in the original, no surname given)
- Isabel, a nun at Sempringham, who received twenty pounds (vynt l) from John. ('Isabell') 
John had six illegitimate sons that I've been able to find. Here's a list of them.
John's most obscure son and only mentioned, that I've found, in a petition presented to parliament in 1334 by one Ralph le Botiller. This petition calls him Ravlyn fitz al Counte de Garrein, "Ravlyn, son of the earl of Warenne," and records le Botiller's complaint that John had sent Ravlyn and some members of his household to attack two of his (le Botiller's) manors in Cheshire and steal or destroy his possessions. Ravlyn is not mentioned either in his father's will of June 1347 or in a letter John sent to Edward III in April 1346 naming his other two secular sons, perhaps because he was dead by then. 
- John and Thomas
By 1316, John de Warenne had two sons by Maud Nerford, and in August that year persuaded Edward II to accept them as his heirs: he surrendered his lands to Edward and received them back "with remainder to John de Warenna son of Matilda de Neirford and the heirs male of his body, and failing such issue to Thomas de Warenna, son of the said Matilda..."  John evidently was the elder of the two and presumably named after their father; Thomas may have been named after Thomas Nerford, one of Maud's brothers.
Confusingly, there are a few references at the beginning of the 1300s to John and William, sons of John, earl of Warenne, both of whom had been, according to letters of the pope, ordained priest while still under age.  As our Earl John was only born in 1286, these two must have been the illegitimate sons of his grandfather John de Warenne (1231-1304), the previous earl of Surrey and Warenne, and thus John's uncles. His sons John and Thomas had both joined the order of the Hospital of St John of Jerusalem by November 1345, and their mother Maud Nerford was dead by then.  Neither of them appeared in their father's will.
Almost certainly another son of Maud Nerford, as he owned lands in Norfolk which had previously belonged to her. John called him "Edward de Warenne, my son" - plain 'Edward', not 'Sir Edward' - in his 1347 will, and left him twenty pounds. Edward was also mentioned in a letter John wrote to Edward III in April 1346, saying that his sons Edward and William were ready to serve the king abroad.  He was presumably born after August 1316 as he was not mentioned in John's land settlements at that time, and before his father "ousted" Maud Nerford from his heart and company in or shortly before 1320. He may have been named in honour of Edward II, or possibly after his father's first cousin Edward Balliol, son of John Balliol, king of Scotland (himself probably named after Edward I). He is named as "Edward de Warenn, knight" in an entry on the Close Roll of 23 February 1349. 
Edward de Warenne married Cecily, daughter of Nicholas de Eton, and founded the Warren family of Poynton, Cheshire. His eldest son, named John after his father, was born in 1343 or 1344; he had other sons named Edward and William. Edward de Warenne had died by 1369, and his son John died in 1392. See this thread for more information.
- Sir William and Prior William
John de Warenne had two sons called William, one a prior and the other a knight, by an unknown mother or mothers. William was the name of John's father, Sir William de Warenne, son of the earl of Surrey who died in 1304 and killed in a jousting tournament in 1286 when John was a baby, so it's not at all surprising that John would use the name for his sons. One of them, probably the knight, had been born by 24 August 1310, when John (then aged twenty-four) granted "his son William de Warenna and the heirs of his body" the manor of Beeston in Norfolk. Although John gave the manor of Beeston to Earl Thomas of Lancaster in 1318, Sir William de Warenne was holding it in January 1333.  It is strange, therefore, that William was not mentioned in John's land settlements of 1316, when John named his sons John and Thomas as his heirs. Perhaps this means that William was not Maud Nerford's son and she persuaded Earl John to make her own sons his heirs? Or perhaps John had envisaged a career in the Church for William, then changed his mind? I can only speculate. On the other hand, Sir William witnessed a grant of land from his father to his (Earl John's) lardener Henry de Kelsterne in January 1332 with Thomas Nerford, Maud Nerford's brother - which may imply a relationship between William and Nerford, or may only mean that John de Warenne held onto his connections to the Nerfords even after his relationship with Maud ended. 
John's other son William was prior of Horton in Kent and of Castle Acre in Norfolk, and was named in numerous papal letters, warrants, writs etc as the illegitimate son of John de Warenne. I don't know the identity of his mother, but according to a declaration of 1338 that he was a true-born Englishman and not a foreigner, he was born at his father's Yorkshire castle of Conisbrough.  In his will, John left "Master [daunz] William de Warenne, my son, a Bible which I had made in French." In October 1348 and again in February 1351, Edward III appointed several sergeants-at-arms to arrest William and a fellow monk of Castle Acre on the grounds that they "have spurned the habit of their order and are vagabonds in England in secular habit" who were "to be chastised according to the rule of their order." William was, according to a papal letter, still alive in early 1364. 
John's son William the knight seems to have been a great favourite of his father, judging by the number of things John bequeathed to "Sir William de Warenne, my son" in his will, which included 100 marks (sixty-six pounds), a silver-gilt helmet and coronet and all his armour for jousting. John also left a gold brooch to William's wife, and although his will didn't give her name, it appears in a papal grant of April 1344: Margaret.  Sir William was one of the three leaders of a company of archers and men-at-arms raised by his father in November 1339, and accompanied his (half-?) brother Edward de Warenne on campaign abroad in April 1346.  Like his (half-?) brothers Edward and William the prior, he was openly and frequently acknowledged as the earl of Surrey's illegitimate offspring and sometimes witnessed John's charters as "the grantor's son," and also received grants of his own from John on occasion. In June 1364, Edward III granted him an annuity of forty marks "for long service," and William was still active in November 1368, when he and other men were accused of hunting without permission in the lands of Hugh Hastings in Yorkshire. 
1) F. Royston Fairbank, 'The Last Earl of Warenne and Surrey and the Distribution of his Possessions', Yorkshire Archaeological Journal, xix (1907), p. 264.
2) Calendar of Chancery Warrants 1244-1326, p. 296.
3) The National Archives SC 8/87/4348.
4) Fairbank, 'Last Earl', pp. 249-250.
5) John's will can be read online in English and the original French.
6) Rotuli Parliamentorum, vol. II, p. 88; TNA SC 8/156/7772.
7) Calendar of Patent Rolls 1313-1317, pp. 528-529; Chancery Warrants 1244-1326, pp. 576-578; TNA SC 8/280/13971.
8) For example, Calendar of Papal Letters 1305-1341, p. 11.
9) Cal Pat Rolls 1345-1348, p. 16.
10) Fairbank, 'Last Earl', p. 248.
11) Calendar of Close Rolls 1349-1354, p. 11.
12) Cal Pat Rolls 1307-1313, p. 330; Cal Pat Rolls 1330-1334, p. 404; Calendar of Fine Rolls 1337-1347, p. 52; TNA C 143/85/11.
13) Cal Pat Rolls 1340-1343, pp. 511-512.
14) Calendar of Inquisitions Miscellaneous 1308-1348, p. 397, and Cal Close Rolls 1339-1341, pp. 18, 82, say that William was born at Conisbrough Castle. See also Cal Papal Letters 1342-1362, pp. 12, 124, 139, TNA SC 8/247/12337.
15) Cal Pat Rolls 1348-1350, p. 244; Cal Pat Rolls 1350-1354, p. 78; Cal Papal Letters 1362-1404, p. 6.
16) Cal Papal Letters 1342-1362, p. 145.
17) Cal Close Rolls 1339-1341, p. 302.
18) Cal Pat Rolls 1338-1340, p. 411; Cal Pat Rolls 1343-1345, p. 570; Cal Pat Rolls 1361-1364, p. 511; Cal Pat Rolls 1367-1370, p. 200.