In 940, Bruno began to exercise the functions of imperial chancellor. After he had received deacon’s orders in 941 or 942, the emperor appointed him, dispite his youth, Abbot of the monasteries of Lorsch, near Worms, and of Corvei on the Weser. In both communities he soon restored the strict observance of Saint Benedict’s Rule. He was ordained priest about 950 and in 951 became archchancellor; even from the year 940 on, all Otto’s state papers were prepared by Bruno’s hand. As the executive administration of affairs was conducted chiefly through the royal chancery, Bruno’s influence no extended to all parts of the empire. Relations between Germany and France were by his good offices greatly improved. He took part in the Synod of Verdun, in 947, and assisted in the adjustment of the quarrel, of such consequence to the Kingdom of France, about the Archbishopric of Reims. In 951 he accompanied the Emperor Otto to Italy. In the troublous times which soon followed during the revolt of Ludolf, Otto’s eldest son and heir-apparent, and Conrad, Duke of Lorraine, Bruno proved his loyalty and devotion to his brother. For this service, after the death (9 July 953) of Wicfrid, Archbishop of Cologne, the emperor caused Bruno to be elected his successor in that see, and likewise entrusted to him the administration of the Duchy of Lorraine. On the 21st of September, the nobility of that province swore allegiance to Bruno at Aachen, and on the 25th he was consecrated and enthroned at Cologne. Through Bruno’s mediation Ludolf was reconciled with his father, and the rebellion of Conrad effectually quelled. In the struggle between the last of the Carlovingians and the rising house of Capet, Bruno’s prestige enabled him to act, in the name of his imperial brother, as a supreme arbitrator in French affairs, countless disputes being satisfactorily settled by his prudence and tact.
In Bruno’s personality as prince-bishop, was represented the perfect union of Church and State which was the corner-stone of the policy of Otto the Great; for Bruno, despite his tireless temporal activities, was a great bishop and zealous pastor. He ruled by personal piety and singular holiness of life. With scrupulous care he watched over the moral discipline of his diocese, improved the higher education of the clergy and lavished his resources on monastic and ecclesiastical institutions throughout the realm. The monastery of Saint Pantaleon at Cologne, begun in 956, was his foundation. The literary distinction to which Lorraine, before other parts of the kingdom, early attained may be accounted not the least remarkable result of his work. Bruno’s favourite abode was Bonn.
When Otto set out a second time for Italy in 961, to be crowned emperor at Rome, the government of the realm and the guardianship of Otto II was confided to Bruno and to William, Archbishop of Mainz. Soon after the kaiser’s return, Bruno was summoned again on a mission of peace to France; it was while on this journey that he died, at Reims. His body, at his own request, was carried back and buried in the monastic church of Saint Pantaleon at Cologne. From time immemorial the Diocese of Tournay has had a special office for Saint Bruno on June the 18th, and as the day of his death was always celebrated at Saint Pantaleon as the anniversary of a saint, the feast of Bruno, Confessor, is now observed throughout the Diocese of Cologne as a double on the 11th day of October.