Pierre I Mauclerc DE DREUX Comte de Dreux, Duc de Bretagne
- Born: 1187
- Married (1): Mar 1213-Oct 1214
- Married (2): 1230
- Married (3): Bef Jan 1236
- Died: Abt 30 May 1250, at sea off Damietta
- Buried: église abbatiale de Saint-Ived, Braine, Aisne, Picardy, France
The Chronicle of Alberic de Trois-Fontaines names (in order) "Henricum archiepiscopum Remensem et tres comites, Robertum de Brana, Petrum de Britannia, Iohannem Masticonesem et eorum sorores numero septem" as children of "comiti de Brana Roberto" and his wife Yolande. He swore allegiance at Paris 27 Jan 1213 to Philippe II "Auguste" King of France as PIERRE I "Mauclerc" Duke of Brittany. Comte de Penthièvre by annexation 1214. He was created Earl of Richmond by Henry III King of England 16 Jan 1219 (confiscated Nov 1224, restored Oct 1229, confiscated again Jan 1235). “Johannes comes Matisconensis” names “frater meus P. comes Britannie” in a charter dated Aug 1234. He surrendered the duchy of Brittany to his son in 1237, after which he is sometimes referred to as PIERRE de Braine. William of Tyre (Continuator) names "Pierre de Drues cuens de Bretaigne" among those who took part in the crusade from France which landed at Acre in 1239. He accompanied King Louis IX on crusade in 1249 and was captured at Faraskur 6 Apr 1250, after being wounded at the battle of Mansurah. He died at sea on his return to western Europe.
Pierre married Alix DE THOUARS Duchess of Brittany, daughter of Guy DE THOUARS Duc de Bretagne and Constance DE RICHEMONT Duchesse de Bretagne, in Mar 1213-Oct 1214. (Alix DE THOUARS Duchess of Brittany was born in 1200, died on 21 Oct 1221 and was buried on 24 Nov 1255 in Abbaye de Notre-Dame, Villeneuve-les-Nantes, France.)
Pierre also married Nicole in 1230. (Nicole died in Feb 1232.)
Her marriage is confirmed by an epitaph at Villeneuve which records the burial of "Nicolle, la mère monsour Olivier de Machecou" read together with the charter dated 10 Mar 1258 under which "Jehan duc de Bretaigne conte de Richemont" confirmed an agreement between "Morice de Belle Ville, par raison de Jehanne sa femme, dame de la Roche sur Yon et de Luçon" and "Olivier nostre frère" concerning "la terre de Machecoul et de Saint Philbert".
Pierre also married Marguerite DE MONTAIGU Dame de Montaigu et de La Garnache[-en-Poitou] before Jan 1236. (Marguerite DE MONTAIGU Dame de Montaigu et de La Garnache[-en-Poitou] was born between 1188 and 1190 and died in 1241.)