He attended the Council of Poitiers, and Bernard and Robert of Arbrissel excommunicated Philip I, king of the Franks.

Desiring to live a life of greater austerity, in 1107 he and his friend Geoffrey (later Abbot of Tiron), build a small house in a solitary place near Fougeres.

[6] The success of the community aroused the jealousy of the Cluniac monks of Saint-Denis of Nogent-le-Rotrou claim tithes and burial fees from Tiron.

Bernard then refounded his monastery on adjacent land in Thiron-Gardais granted to him by Bishop Ivo of Chartres.

[6] With the aid of donations from the kings and nobles of France, England and Scotland, Bernard established the Abbey of the Holy Trinity of Tiron in 1114.

From here Bernard founded the Tironensian Order, based on a strict observance of the Rule of Saint Benedict and an emphasis on manual labour.