The second chapter continues the investigation of sacrum imperium, demonstrating that while the imperial chancery used the term more and more frequently, it was only the strong Italian presence at court that kept influencing the imperial notaries to use it and other correlated terms. It is also made clear that the converse was true: when there were no Italians at court, this kind of terminology was not used, even as late as the 1220s. The investigation shows, contrary to expectations, that cities where this terminology was used could be identified, and occasionally even individuals could be pinpointed. Moreover, the presence of courtiers or diplomats from the city of Rome is clearly correlated to the appearance of the tripartite title of the Empire (sacrum Romanum imperium and sacrum imperium Romanum). Thus, the most commonly used title of the Empire for most of its existence was not only invented by the Romans, as Jürgen Petersohn demonstrated, but it was also propagated by them to the rest of the Empire and the world.

In the fourth chapter, Sulovsky turns to the supposedly imperial saints’ cults of the 1160s: the Three Kings and Saint Charlemagne. The chapter demonstrates that the cult of the Magi was unconnected to the emperor. Rather, the agency of Rainald of Dassel in bringing the Magi to Cologne was related to his personal suffering from the Milanese while he was imperial legate in their city on the eve of Epiphany (= Three Kings’ Day). As this was liturgically already the vigils of Epiphany, and as Rainald was trapped in the imperial palace next to the saintly bodies before he barely escaped, he translated the Magi to honour his protectors. This debunks the Kulturkampf-inspired theory that the purpose of worshipping the holy kings who adored Christ long before the apostles were called would help achieve a sacral independence of the Empire from the Papacy. On the other hand, the cult of Saint Charlemagne is shown to have been accepted at the imperial court as a part of a plan to mend the Alexandrine schism by launching an Anglo-Franco-German crusade, which was thought of as an imitation of Charlemagne’s exploits in the east.

The conclusion draws upon the findings of all the chapters to argue that Barbarossa scholars had often studied more a construct of post-Kulturkampf Germany than the medieval emperor himself. Rather than a sacraliser of the state who teamed up with Reichskanzler Rainald of Dassel (a stand-in for Otto von Bismarck) in order to hammer the Papacy into submission, Frederick I was a ruler determined to restore the greatness of the Empire by many different means, including papal and Arab alliances. This has been overlooked because of the dearth of sources for the later part of his reign, and because of the profound misunderstanding of Frederick’s Aquensian projects. By dismantling the historiography in an archaeological way, Sulovsky restores the connections apparent in the sources, and makes it clear that the increasing Romanisation of the Empire had radical consequences for authority and its expressions, both for the pope and the emperor. Therefore, much of what was described as a deliberate sacralisation of the Empire in opposition to the Papac, was in fact its gradual Romanisation. This was not a project spearheaded by German court, but by the self-conscious Italians, who wanted a Roman emperor to represent them, and not a German king.

The introduction explains the state of the scholarship regarding the sanctity of the state, starting with what is commonly believed. Sulovsky then traces the argument back to its intellectual roots, in the process showing that it is based on false premises that had more to do with the clash of Catholic and Protestant worldviews than with any medieval reality per se. The introduction of the phrase sacrum imperium, the translation of the Three Kings and the canonisation of Saint Charlemagne constituting a triad of sacralising acts is traced to Heinrich Appelt, the senior diplomatist who edited Frederick I’s diplomata. However, as Sulovsky shows, Appelt drew heavily upon Friedrich Heer, whose magnum opus Die Tragödie des Heiligen Reiches deeply influenced many scholars, though he is only reluctantly cited by them. Heer’s work is then shown to be a Catholic response to the Kulturkampf-dominated Prussian school, which formulated the original idea of the sacralisation of the state in 1910, but based on eighteenth-century German Protestant interpretations of imperial history. Thus, the introduction demonstrates that much of our knowledge rests on the presuppositions and axioms of a bygone ideological struggle.

The first chapter deals with the phrase sacrum imperium in the period 1125–1167. It starts out as a rare occurrence in imperial Italy when the locals sought German imperial assistance and, at the same time, a staple phrase used by Latin diplomats to address the Byzantine emperor. However, Sulovsky shows that after the Second Crusade (1147–1149), the German imperial court increasingly adopted elements of the sacral terminology of the state, as used in the Byzantine east, when dealing with Italian affairs. When Barbarossa’s second Italian campaign (1158–1162) was being planned in early 1157, the term sacrum imperium finally appeared in a document issued by the imperial chancery. However, whereas previous scholars could not tell who the author behind the text was, Sulovsky argues that it was the senior notary Albert of Sponheim, who had introduced other innovations as well, and who had taken part in both the aforementioned crusade and in Frederick’s first Italian expedition as a high-level diplomat. Moreover, Albert adopted sacrum imperium both from the Italian and Byzantine usages to the German one, so that he could convince the letter’s addressee, his fellow crusader Otto of Freising, to join the Italian war.