Around 1100, Abbot Pierre wrote two books on the founding and construction of the Abbey of Maillezais. The new church was consecrated in 989 by
Gombald,
Archbishop of Bordeaux. Father Gausbert, cousin of Countess Emma, brought thirteen monks from Église Saint-Julien de Tours to create a
Benedictine abbey, first settling in
Saint-Pierre-le-Vieux, Vendée, about north of the current ruins. The abbey's jurisdiction later passed from Église Saint-Julien de Tours to Église Saint-Cyprien in
Poitiers. In 1010, the Saint-Pierre-le-Vieux abbey moved to Maillezais, with groundbreaking for a new Maillezais chapel, soon after again dedicated to Saint Pierre (St. Peter).
William V, Duke of Aquitaine was buried at the abbey's cloister in 1030. In 1225,
Geoffroy d'Estissac, who was envious of Maillezais, attacked and looted the abbey. Excommunicated from the church, he went to Rome and apologized to the Pope in the presence of the abbot of Maillezais for his wrongful deeds. After he was pardoned, he restructured it with additional bays extending the nave. Under Abbot Geoffroy II Povereau in the early 14th century, it was a large property consisting of churches, priories, and large fertile land. The refurbishing of the cathedral was continued, and in the middle of the 14th century a Gothic transept was added and a bell was also provided. There were many improvements to the cathedral's interiors such as better furnishings, conversion of the abbot's residence into an episcopal palace, building of a monastery dormitory near the second cloister. However, what remains among the ruins of the cathedral are its eastern and southern wings. Among other bishops of the cathedral were Guillaume de Lucé (1421–38) and Thibaud de Lucé (1438–55), who were political counselors to
Charles VII. Further improvements took place when Geoffrey d'Estissac of Périgord became the bishop in 1518. It was the last refurbishing done and the additions made were the choir of the cathedral and also the castle of Coulonges on l'Autise. During the period after 1528, when Rabelais had been in charge of the monastic order from 1524–28, there was internecine war between the Catholics and the Protestants. The cathedral was destroyed in 1562 in the course of the
Reformation and subsequent
Wars of Religion. In 1589,
Agrippa d'Aubigné, a Protestant, a scholar and a poet, became the bishop and fortified the cathedral with a watch tower. The fort became a stronghold of the Protestants for the next thirty years till the Duke of Rohan succeeded him. When during the late 16th and early 17th century the Protestants of the
Huguenots had converted it into a fort-like structure, the Catholics had to even baptize their children outside the city limits. It remained under the control of the Protestants till 1618. But by 1619 the cathedral was back under the control of the Catholics and
Henri de Sourdis became the Bishop. In 1629, the
Bishopric of Maillezais was one of the richest in France with a lease value of 35,000
livres. It remained the seat of the Bishopric of Maillezais until 1648, when
Pope Innocent X transferred the bishopric to the
St. Louis Cathedral of La Rochelle, in the
Diocese of La Rochelle. The
monastic community continued at the Maillezais site until 1666, when the entire site was abandoned. The cathedral site remained dormant till after the
French Revolution when it was sold as
national property to serve as a stone quarry. In 1840, it was returned to the people, who decided to maintain the cathedral as a heritage monument. It was designated a historical monument on 30 January 1924. It was only after 1996 that the General Council of the Vendée took interest in its restoration. ==Architectural and archaeological remains==