When monastic discipline was well established at Gembloux, Erluin attempted, at the suggestion of Count Regnier of Hainaut, to reform
Lobbes Abbey in what is now Belgium in 955. The monks of Lobbes however did not welcome reform, and on the night of 20 October 958 three of them assaulted Erluin in his cell, dragged him outside the monastery and inflicted on him serious bodily injuries. Erluin died at Gembloux on 10 August 986 after
Pope Benedict VII had granted his monastery
exemption and papal protection. During the short reign of his successor, abbot Heriward (987-990), the monks voluntarily relinquished their right of exemption in favour of Bishop
Notger of Liège, who was well disposed towards the monastery. Heriward was succeeded by
Erluin II (990-1012), under whose weak administration monastic discipline greatly relaxed. His successor Olbert (1012-1048), a pious and learned abbot, restored discipline, built a new abbey church in 1022, organized a rich library, and by encouraging sacred and secular learning gave the first impulse to the subsequent flourishing condition of Gembloux. During the period of its greatest intellectual activity the abbey was ruled by Mysach (1048-1071), Thietmar (1071-1092), Liethard (1092-1115) and
Anselm (1115-1136). Under Thietmar flourished the famous chronicler
Sigebert of Gembloux (1030-1112), who in a neat Latin style wrote a chronicle of the world from 381-1111, a history of the abbots of Gembloux and other historical works of great value. His chronicle was continued by Abbot Anselm till 1136, and his history of the abbots of Gembloux by the monk
Gottschalk, a disciple of Sigebert. The learned prior Guerin, a famous teacher at the abbey school, was a contemporary of Sigebert. ==Decline==