As Archbishop, William undertook several ecclesiastical reforms and became popular with the people of York. However, he still needed a
pallium, the sign of an archbishop's authority from the Pope, which he had not yet received. The Cistercians, who were still adamantly opposed to his being Archbishop, were determined to prevent his receiving it. William travelled to Rome in an attempt to obtain the pallium. The election of Pope Eugene III, a Cistercian, in 1145, was a setback for his cause.
Bernard of Clairvaux, the famous Cistercian abbot and religious leader, exerted all his influence to ensure William's suspension, sending a series of complaints to the new Pope that William had been intruded by secular powers into the see, that he was oppressing the Cistercian monasteries and that he had irregularly appointed
William of St. Barbara as
Dean of York. In the winter of 1145–1146 Eugene re-examined the case, declared that William had not been validly consecrated and suspended him from office. William was required to obtain an in-person refutation of the old charges by William of St Barbara, by then the
Bishop of Durham. William was formally deposed by Eugene in early 1147 and the deposition was confirmed at the
Council of Reims on 21 March 1148. Another election to York was held, and the candidates included
Hilary of Chichester, who was the king's candidate, and Henry Murdac, the Cistercian
abbot of Fountains Abbey. Murdac's supporters included the Cistercians and most of the clergy of the diocese, including William's former ally, William of St Barbara. Both sides appealed to the Pope, and the Pope confirmed Murdac as the successful candidate. ==Second archiepiscopate==