By appointing Bruno to the vacant position, Otto provided himself with a powerful ally against Conrad (much of Lotharingia fell under the archdiocese of Cologne) just when he needed one most.

The combined positions of archbishop and duke — or archduke, as his biographer Ruotger called him — made Bruno the most powerful man after Otto not just in Germany but also beyond its borders.

Indeed, Otto delegated to Bruno and his successors as archbishop a number of normally royal privileges — the right to build fortifications and set up markets, to strike coins and collect (and keep) such taxes as the special ones on Jews in return for royal protection, those on market trading and tolls from traffic along the Rhine.

Even though Bruno's successors as archbishops would not be dukes as well, they would be the secular as well as the ecclesiastical rulers of Cologne until the battle of Worringen three centuries later.

Bruno's court in Cologne was the main intellectual and artistic centre of its period in Germany — far more so than that of his brother Otto, which was far more peripatetic and militarily oriented.

The historian Jonathan Wright [de] situates the promotion of his cult against the background of the Kulturkampf.

That is, it stemmed from a desire to preserve the Catholic identity of Cologne as it was drawn into the Protestant dominated German Empire.