1022 founded Troarn Abbey.
Note: Turton has Roger as son of Hugh & Josceline, rather than Roger being married to Josceline. After reading the evidence for CP's ancestry in note (c) below, I can see Turton's point. It seems that Turton's interpretation is just as valid as CP's. Turton goes by the "fact" that Josceline married a Hugh de Montgomery and had a son Roger, while CP goes by the "fact" that Josecline was mother of Roger II. One of the "fact"s is wrong. But I think the dates favor Josceline being a grandmother of Roger II, rather than a mother; so I am going with Turton.
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ROGER I DE MONTGOMERY, seigneur of Montgomery and vicomte of the Hiesmois, witnessed in 1031 or 1032 a charter of Robert I, Duke of Normandy, for the abbey of St. Wandrille. Between 1028 and 1035 he restored to the abbey of JumiËges a market at Vimoutiers, near Montgomery, of which he had deprived the monks. During the troubles of Duke William's minority he was exiled and went to Paris on account of the murder of Osbern, son of Herfast, the steward, by his son William de Montgomery. At some date unknown he founded a collegiate church for twelve secular canons at Troarn. He married Josceline, a niece of the duchess Gunnor (c). The date of his death is uncertain. [Complete Peerage XI:682-3, (transcribed by Dave Utzinger)]
(c) Robert de Torigny in his continuation of William de Jumieges (bk. viii, chapter 35--ed. Marx, p. 321) makes the mother of Roger II de Montgomery to be Josceline, daughter of Wevie, a sister of Gunnor; in chapter 37 he states Wevie's husband Hugh de Montgomery, but the father of Roger II was undoubtedly named Roger. The mistake in these genealogical chapters, 35-37, as to which see G. H. White's article on "The Sisters and Nieces of Gunnor, Duchess of Normandy" in 'Genealogist', N.S., vol. xxxvii, pp. 57-65, 128-132, are too numerous to make it possible to trust them in default of corroboration, but the statement as to Josceline is in part corroborated by Ives, bishop of Chartres. In a letter of the year 1114 to Henry I ('Rec. des Hist. de France', vol. xv, p. 167) he points out that a projected marriage between a natural daughter of the King and Hugh, son of Gervase de Chateauneuf, would be invalid on the ground of consanguinity. He traces Hugh's pedigree as follows: Senfrie, sister of Gunnor, had a daughter, Josceline, the mother of Roger de Montgomery, who had a daughter Mabel married to Gervase de Chateauneuf, by whom the daughter of Senfrie or Sainfrie, who according to Robert de Torigny (loc. cit.) was Gunnor's sister; the name of Josceline's husband is not given. The bishop seems to be writing with due sense of responsibility, for the letter contains this remarkable passage: " Quod enim dicimus, non ex conjecturis facimus, quia prae manibus habemus scriptam genealogiam, quam scribi fecerunt nobiles viri de eadem tribu progeniti, et parati sunt ante judices ecclesiasticos eandem genealogiam in tuto loco computare et secundum legum instituta probare." Moreover the protest was successful, since Hugh did not marry the King's daughter but a daughter of Waleran, Count of Meulan. If however another of these genealogies of Robert de Torigny be accepted, Hugh nevertheless married within the prohibited degrees, since his bride descended from another of Gunnor's sisters (see 'ante', vol. vii, p. 521, note "c"). Taken as a whole the evidence seems to show that Rober I's wife was Josceline, a niece of Gunnor.