Following William Rufus' accession to the throne in 1087, St-Calais is considered by scholars to have been the new king's chief advisor.

William Rufus laid siege to St-Calais in the bishop's stronghold of Durham, and later put him on trial for treason.

[4] St-Calais studied under Odo, Bishop of Bayeux, the half-brother of the future William I of England, who was then Duke of Normandy.

[8][9] His elevation may have been a reward for diplomatic services he rendered to the king in France,[10] or to help secure the see from further disorder following the death of the previous bishop, Walcher, during a feud.

Symeon of Durham stated that St-Calais was chosen as a bishop for this reason,[11] describing him as "very well versed in sacred and secular learning, very conscientious in matters of divine and worldly business, and so remarkable for good conduct that he had no equal amongst his contemporaries".

[13] After his appointment, St-Calais decided to replace his cathedral chapter of secular clergy with monks, and consulted the king and Lanfranc, the Archbishop of Canterbury, before going to Rome to receive permission from Pope Gregory VII.

[15] In 1083 he expelled the married clergy from the cathedral,[16] and moved a small community of monks from Bede's old monastery at Jarrow to Durham, to form the new chapter.

[17] After the community had settled in Durham, St-Calais named Eadwine as prior, and arranged for lands to be set aside to support the monks.

[19] St-Calais also gave a set of constitutions to the cathedral chapter, modeled on Lanfranc's rule for Canterbury.

The pope was also concerned about the king's refusal to allow the delivery of papal letters to the English bishops unless royal permission was secured.

[32] Soon after the accession of William Rufus, St-Calais became one of the king's most trusted lieutenants,[33] along with the recently released Odo of Bayeux.

[3] Some historians, including W. M. Aird, have suggested that St-Calais felt the division of the Conqueror's realm between two sons was unwise.

The rebellion had failed by the end of the summer,[39] but St-Calais continued to hold out in Durham, at first claiming he had never actually rebelled.

When the king's army arrived, St-Calais agreed to come out, but only after receiving a safe conduct that would allow him to attend a trial while his men continued to hold the castle.

Lanfranc presented the king's case, declaring that the confiscated lands had been held as fiefs, and thus St-Calais could be tried as a vassal, not as a bishop.

Those judging the case held that because St-Calais never answered the formal accusation, and because he appealed to Rome, his fief, or lands, was forfeit.

[41][43][44] Although St-Calais claimed to be defending the rights of clergy to be tried in clerical courts and to appeal to Rome, his fellow bishops believed otherwise.

Most of the bishops and barons that judged the case seem to have felt that the appeal to Rome was made to avoid having to answer an accusation that St-Calais knew was true.

"[47] The extant De Iniusta Vexacione Willelmi Episcopi Primi, or Of the Unjust Persecution of the Bishop William I,[48] details the trial of St-Calais before the king.

[49] After the court adjourned, St-Calais was held as a prisoner at Wilton Abbey until his followers in Durham relinquished the castle.

[40] Once the castle was back under the king's control, St-Calais was released, and exiled; he left for Normandy,[40] and no more was heard of his appeal to Rome.

Both the English king and St-Calais did all in their power to support Malcolm's sons, who had been educated in England, in their attempts to secure the Scottish throne.

[2] Later, in 1095, an English noble, Robert de Mowbray, who was Earl of Northumbria, challenged the bishop's authority in the north.

This arose because St-Calais did not make a formal division of the diocesan revenues between the bishop's household and the monks of the chapter.

[74] Shortly before Christmas 1095, one of St-Calais' knights, Boso, fell ill and dreamed he was transported to the afterlife, where he found a large house with gates made of iron.

[76] The king had summoned St-Calais shortly before Christmas to answer an unknown charge, and it is possible that the stress of this threat caused his death.

[5] Besides his copy of the Decretals, he left at his death over fifty books to the monks of Durham, and the list of those volumes still exists.

The construction technique of combining a pointed arch with another rib allowed a six-pointed vault, which enabled the building to attain a greater height than earlier churches.

The technique of the six-pointed vault spread to Saint-Etienne in Caen from which it influenced the development of early Gothic architecture near Paris.