Tonsured at the Benedictine Abbey of Saint-Cyprien in Poitiers around the year 1070, Bernard left the order in 1101 when his nomination as new abbot was disapproved by Cluny and Pope Paschal II. From then on Bernard lived first as a hermit on the island of Chausey, between Jersey and Saint-Malo, then in the woods of Craon, near Chartres, with two other rigorist monks: Robert d'Arbrissel, future founder of the controversial Abbey of Fontevraud, and Vitalis de Mortain, later the founder of the Congregation of Savigny in 1113. Following the example of the Desert Fathers, all three men and their followers (men and women) lived detached from the world, in great poverty and strict penance. However, there is strong evidence suggesting that following their retreat into the forest, Bernard, Robert and Vitalis were following the Celtic Rite, independently of and in opposition to the Roman Catholic Church, and under the protection of the Duchy of Brittany.
Within less than 5 years of its creation, the Order of Tiron owned 117 priories and abbeys in France, England, Wales, Scotland and Ireland. In Scotland, the Tironensians were the monks and master craftsmen who built and occupied (until the Reformation) the abbeys of Selkirk (1113), Kelso (1128), Arbroath (1178), and Kilwinning (1140+), the legendary birthplace of Freemasonry. In France, the Order was integrated into the new Benedictine Congregation of St. Maur in 1627.