Constance's father Conan IV had reunited the Duchy of Brittany in wars with Henry II of England. After the wars with Henry II, Conan IV faced rebellions from some Breton nobles. He appealed to Henry II for assistance in putting down those rebellions. In 1166, Henry invaded Brittany in order to punish the local barons' revolt. In order to gain complete control over the duchy, he forced Conan IV into abdicating in Constance's favor and betrothing her to his fourth legitimate son Geoffrey. Five-year-old Constance succeeded him as Duchess of Brittany. She spent her youth at the English court. In February 1171, Conan IV died. Although his daughter Constance was the heiress of the Earldom of Richmond, she did not enter her inheritance until 1183/1184. In 1181, twenty-year-old Constance was forced into marriage with Geoffrey. On August 19, 1186, Geoffrey was trampled to death in a riding accident during a tournament in Paris. Constance thereafter became the effective ruler of Brittany. However, on 3 February 1188, Henry II of England arranged for Constance to marry Ranulf de Blondeville, 6th Earl of Chester, one of the most powerful earls in England. Though Ranulf used, not consistently, the style Duke of Brittany, he never had the control of the duchy, and is not known to have played an important role there, and the Bretons, as well as Constance, never acknowledged him as Duke jure uxoris, and excluded him from the government of the Duchy. In 1191, King Richard I of England officially proclaimed his nephew, Constance's son Arthur as his heir in a treaty signed with Philip II of France. To promote her son Arthur's position and inheritance, Constance included him in the government of the Duchy in 1196. In response to this act that thwarted his projects, Richard summoned her to Bayeux and had her abducted by Ranulf in Pontorson and imprisoned in Saint-James de Beuvron. He spread the rumour that Constance had been imprisoned for matrimonial reasons. As a result, rebellions were sparked across Brittany on her behalf and Arthur was sent to Brest. Richard demanded that hostages were delivered to him in exchange for Constance's freedom. The Bretons agreed but Constance and the hostages remained imprisoned and rebellions went on. Richard eventually bowed to growing pressure and had the Duchess released in 1198. Back in Brittany, Constance had her marriage annulled. On 1 June 1199, Pope Innocent III eventually decided that the Archbishopric of Dol should be subordinated to the Metropolitan of Tours and deprived the Archbishop of his title and pallium. The Archbishopric then became a Bishopric again. Constance disagreed with this decision that gave an advantage to Philip Augustus over Brittany and was consequently excommunicated. Constance took Guy of Thouars as her next husband in September or October 1199. Between 1198 and the time of her death delivering twin daughters, Constance ruled with her son Arthur as co-ruler. Throughout these years, Constance advised her son towards a French alliance, pursuing the policy of her late husband Geoffrey II.
Family
As a girl, Constance could not inherit the duchy at her father's death if she had a brother. A charter by Margaret, Constance's mother, seems to show that she and Conan had more than one child. However, two charters made by Constance and her son Arthur towards 1200 mention a brother of Constance, William "clericus". As a boy, William should logically have inherited the duchy after Conan. According to Everard, Henry II's forcing Constance's father into abdicating in 1166 was meant to prevent any son of the Duke from inheriting the duchy. Constance and Geoffrey had three children:
Eleanor, Fair Maid of Brittany
Matilda
Arthur I, Duke of Brittany - Geoffrey's posthumous son
Several sources indicate that Constance might have had a third daughter by Guy:
Margaret of Thouars ; she was the first wife of Geoffrey, Viscount of Rohan
Death and Burial
Constance died, age 40, on 5 September 1201 at Nantes. She was buried at Villeneuve Abbey near Nantes, which she had founded earlier that year. Constance's cause of death is debated. The Chronique de Tours indicate that she died of leprosy but this statement is doubtful. It is also believed that she died from complications of childbirth, shortly after delivering twin daughters.
