information:extraction
Rise to power

Eager to restore the Empire to the position it had occupied under Charlemagne and Otto I the Great, the new king saw clearly that the restoration of order in Germany was a necessary preliminary to the enforcement of the imperial rights in Italy. Issuing a general order for peace, he made lavish concessions to the nobles. Abroad, Frederick intervened in the Danish civil war between Svend III and Valdemar I of Denmark and began negotiations with the Eastern Roman Emperor, Manuel I Comnenus. It was probably about this time that the king obtained papal assent for the annulment of his childless marriage with Adelheid of Vohburg, on the grounds of consanguinity (his great-great-grandfather was a brother of Adela's great-great-great-grandmother, making them fourth cousins, once removed). He then made a vain attempt to obtain a bride from the court of Constantinople. On his accession, Frederick had communicated the news of his election to Pope Eugene III, but had neglected to ask for papal confirmation. In March 1153, Frederick concluded the Treaty of Constance with the Pope, wherein he promised, in return for his coronation, to defend the papacy, to make no peace with king Roger II of Sicily or other enemies of the Church without the consent of Eugene, and to help Eugene regain control of the city of Rome.