His contributions to Central European society and culture include the re-establishment of the Corpus Juris Civilis, or the Roman rule of law, which counterbalanced the papal power that dominated the German states since the conclusion of the Investiture controversy.

[4][5][6] Modern researchers, while exploring the legacy of Frederick, attempt to untangle legend from historical reality—these efforts result in new perspectives on both the emperor as a person and the social developments associated with him.

[9] He took part in several Hoftage during the reign of his uncle, King Conrad III, which were a form of informal and irregular assembly popular among the nobles of the Holy Roman Empire.

[11] Conrad III attempted to lead the army across Anatolia but finding this too difficult in the face of constant Turkish attacks near Dorylaeum, decided to turn back.

[21] Abroad, Frederick intervened in the Danish civil war between Svend III and Valdemar I of Denmark[22] and began negotiations with the Eastern Roman Emperor, Manuel I Comnenus.

[23] 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).

[citation needed] As a sign of good faith, Frederick dismissed the ambassadors from the revived Roman Senate,[23] and Imperial forces suppressed the republicans.

The next day, 18 June 1155, Adrian IV crowned Frederick I Holy Roman Emperor at St Peter's Basilica, amidst the acclamations of the German army.

From there, a combination of the unhealthy Italian summer and the effects of his year-long absence from Germany meant he was forced to put off his planned campaign against the Normans of Sicily.

As part of his general policy of concessions of formal power to the German princes and ending the civil wars within the kingdom, Frederick further appeased Henry by issuing him with the Privilegium Minus, granting him unprecedented entitlements as Duke of Austria.

In an attempt to create comity, Emperor Frederick proclaimed the Peace of the Land,[35] written between 1152 and 1157, which enacted punishments for a variety of crimes, as well as systems for adjudicating many disputes.

[38] Disgusted with the pope, and still wishing to crush the Normans in the south of Italy, in June 1158, Frederick set out upon his second Italian expedition, accompanied by Henry the Lion and his Saxon troops.

[39] This expedition resulted in the revolt and capture of Milan,[40] the Diet of Roncaglia that saw the establishment of imperial officers and ecclesiastical reforms in the cities of northern Italy,[41] and the beginning of the long struggle with Pope Alexander III.

[20] In 1164, Frederick took what are believed to be the relics of the "Biblical Magi" (the Wise Men or Three Kings) from the Basilica di Sant'Eustorgio in Milan and gave them as a gift (or as loot) to the Archbishop of Cologne, Rainald of Dassel.

[52] In the meantime Frederick was focused on restoring peace in the Rhineland, where he organized a magnificent celebration of the canonization of Charlemagne at Aachen, under the authority of the antipope Paschal III.

This time, Henry the Lion refused to join Frederick on his Italian trip, tending instead to his own disputes with neighbors and his continuing expansion into Slavic territories in northeastern Germany.

In 1167 Frederick began besieging Ancona, which had acknowledged the authority of Manuel I;[54] at the same time, his forces achieved a great victory over the Romans at the Battle of Monte Porzio.

[55] Heartened by this victory, Frederick lifted the siege of Ancona and hurried to Rome, where he had his wife crowned empress and also received a second coronation from Paschal III.

[55] His campaign was halted by the sudden outbreak of an epidemic (malaria or the plague), which threatened to destroy the Imperial army and drove the emperor as a fugitive to Germany,[56][57] where he remained for the ensuing six years.

During this period, Frederick decided conflicting claims to various bishoprics, asserted imperial authority over Bohemia, Poland, and Hungary, initiated friendly relations with Manuel I, and tried to come to a better understanding with Henry II of England and Louis VII of France.

Later on, Frederick camped in Philippopolis, then in Adrianople in the autumn of 1189 to avoid the winter climate in Anatolia, in the meantime, he received imprisoned German emissaries who were held in Constantinople, and exchanged hostages with Isaac II, as a guarantee that the crusaders would not sack local settlements until they depart the Byzantine territory.

Saladin so greatly feared his approach that he ordered the walls of Laodicia, Gibelet, Tortosa, Biblium and Beyrout, to be pulled down, sparing only the fortresses, that is the citadels and towers.Frederick's death caused several thousand German soldiers to leave the force and return home through the Cilician and Syrian ports.

[105][108][109] The unexpected demise of Frederick left the Crusader army under the command of the rivals Philip II and Richard, who had traveled to Palestine separately by sea, and ultimately led to its dissolution.

He returned home after he signed the Treaty of Ramla agreeing that Jerusalem would remain under Muslim control while allowing unarmed Christian pilgrims and traders to visit the city.

[citation needed] The increase in wealth of the trading cities of northern Italy led to a revival in the study of the Justinian Code, a Latin legal system that had become extinct centuries earlier.

Frederick, however, desired to put the pope aside and claim the crown of old Rome simply because he was in the likeness of the great emperors of old, who tended to have a domineering role over the church, Caesaropapism.

His hair is golden, curling a little above his forehead ... His eyes are sharp and piercing, his beard reddish [barba subrufa], his lips delicate ... His whole face is bright and cheerful.

His shoulders are rather broad, and he is strongly built ...In the opinion of Norman Cantor, Frederick's charisma led to a fantastic juggling act that, over a quarter of a century, restored the imperial authority in the German states.

[123] Another legend states that when Barbarossa was in the process of seizing Milan in 1158, his wife, the Empress Beatrice, was taken captive by the enraged Milanese and forced to ride through the city on a donkey in a humiliating manner.

[133] In Italy, the scholarly attention towards Frederick's person and his reign is also considerable,[134] with notable contributions including Franco Cardini's sympathetic 1985 biography[135] or the 1982 work Federico Barbarossa nel dibattito storiografico in Italia e in Germania, edited by Manselli and Riedmann, considered by Schumann to be a definite synthesis of non-nationally oriented historiography approaches (combining German and Italian research results) of the last forty years.