[1] Having lost her mother in 1070, at only two years of age, she received an education, possibly at the abbey of Ronceray,[2] and grew to be pious and concerned about religious reform, especially the struggle against the secular appropriation of church property.

She also had a habit of retiring in bad temper to a cloister after an argument, cutting off all contact with the outside world, before suddenly making a reappearance in the court as if her absence had never occurred.

[7] In 1092[8] or 1093, her father married her to Duke Alan IV of Brittany,[1] probably to secure an alliance against Normandy, then controlled by William the Conqueror's son, Robert Curthose.

[12] Robert of Arbrissel, whom she kept correspondence with, told Ermengarde that it was her "duty to remain in the world, despite your desire to leave it, and to fulfill God's will concerning you.

[13] It was not uncommon that noblewomen were better educated and more literate than noblemen during the Middle Ages as women were often expected to maintain their own properties and those of their husbands.

[3] Some scholars such as Shawn Madison Krahmer have noted that the letters surviving from St. Bernard of Clairvaux to Ermengarde show a level of intimacy and fondness that would suggest a close friendship between the two rather than a simply advisory correspondence.

[1] Despite being a time of political instability in Brittany,[2] Ermengarde proved to be a popular and effective ruler maintaining stability during the Duke's absence by utilizing her familial ties and alliances.

Ermengarde was also effective in her political role by having close ties and a level of influence over the church, becoming an important supporter of reforms.

[21] Following Fulk's departure for the Holy Land to become King of Jerusalem (c. 1128), Ermengarde was allowed to become a Cistercian nun by St Bernard of Clairvaux at the Priory of Larrey near Dijon in 1130.

She later spent some time at the convent of Saint Anne in Jerusalem until her brother was deposed in a revolt led by Count Hugh II of Jaffa.

[8][22] Ermengarde at one point went on crusade to Palestine; she returned ten years later, and some historians believe her life ended in Jerusalem at the convent of Saint Anne.