After making pilgrimages to various Christian shrines, he eventually retired to live near Grosseto in Tuscany and died in February 1157.
After his death, many pilgrims visited his grave, and some remained in the area to practice his life of prayer and penitence.
)[5] In 1255, the priors of the Hermits of St. Augustine, those of St. William, and also some smaller groups were invited to meet in Rome, with an eye to merging them into one mendicant congregation.
When, in 1256, Pope Alexander IV expanded the Hermits of St. Augustine, many of the Williamites withdrew from the union and were permitted to exist as a separate body under the Benedictine Rule.
In 1435 the order, which about this time numbered 54 monasteries in three provinces of Tuscany, Germany and France, received from the Council of Basle the confirmation of its privileges.
Sometime after 1274, members of the Williamites who had not merged with the Hermits of St. Augustine, were given the abbey of Blancs-Manteaux in Paris, where they followed the Rule of Saint Benedict.