However, Henry II of England arranged for Constance to marry Ranulph de Meschines, 4th Earl of Chester on 3 February 1188. In 1191 King Richard I of England officially proclaimed his nephew, Constance's son Arthur of Brittany, as his heir in a treaty signed with Philip II of France. To promote her son's position and inheritance, Constance abdicated in his favor in 1194.
Constance's marriage with Ranulph deteriorated, with Ranulph imprisoning Constance in 1196. With Constance imprisoned in England, rebellions were sparked across Brittany on her behalf. Ranulph bowed to growing pressure and had the Duchess released in 1198.
Back in Brittany, Constance had her marriage annulled. Later in 1198 at Angers, Constance took Guy of Thouars as her 'second' husband. Throughout these years, Constance advised her son towards a French alliance, pursuing the policy of her late husband Geoffrey II.
When Richard I died in 1199, Phillip II agreed to recognize Arthur as count of Anjou, Maine, and Poitou, in exchange for Arthur swearing fealty to Phillip II, becoming a direct vassel of France. However 13-year-old Arthur was captured while besieging Mirabeau, and the following year he was transferred to Rouen, under the charge of William de Braose, and then vanished mysteriously in April 1203.
During the conflict, Constance's eldest daughter Eleanor was captured and imprisoned at Corfe Castle in Dorset, where she remained imprisoned until her death.
Constance bore her third husband twin daughters; Alix of Thouars, who married Peter de Dreux, first Breton ruler of the House of Dreux; and Katherine of Thouars (1201-c. 1240) who married Andre III of Bretagne, Sire of Vitre.
Constance's cause of death is debated. Some historians believe she died of leprosy. Others believe she died from complications of childbirth, shortly after birthing twin girls. Still others believe that she had leprosy, leading to a difficult delivery, and ultimately to her death shortly after the birth of the twins, thus both leprosy and childbirth being the causes of death. That Constance was birthing twins, at the age of forty, in the unsanitary conditions of the age, should be taken greatly into account in this debate. As the exact date of the twins birth is not currently known, and may never be known, there may never be a resolution to this question.
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