[2] In Spring 1062, he entered the political realm as a member of the faction surrounding Anno II of Cologne, who forcibly took control of the regency of the young king, Henry IV in the Coup of Kaiserswerth.
In 1069 he presided over the assembly of Worms, at which Henry IV announced his intention to repudiate his wife Bertha.
[5] In 1072, under the pretext of a pilgrimage to Santiago de Compostela, he sojourned at Cluny, where he met the Abbot Hugh the Great.
Yet later that same year, when Gregory VII excommunicated Henry IV, Siegfried did an about-face and, at a general assembly of German Aristocrats in Tribur in October 1076, participated in the election of an anti-king, supporting the nobility opposing the Emperor in the civil war that became known as the Great Saxon revolt.
Nonetheless, on 25 March 1077, he crowned Henry IV's brother-in-law, duke Rudolf of Rheinfelden as Antiking, since the allied rebels of which he was a part needed the military prestige and might of a king to offset the power of the established monarch given his rapprochement with the Pope.