On June 18, 1155, Pope Adrian IV crowned Frederick I Barbarossa Roman-German Emperor. From the article:
"CATHOLIC ENCYCLOPEDIA: Frederick I
German King and Roman Emperor, son of Frederick of Swabia (d. 1147) and Judith, daughter of Henry the Black; born c. 1123; died 10 June, 1190. Connected maternally with the Guelphs, he seemed destined to effect a reconciliation between them and the Ghibellines. In 1146 he had already roused public attention by a determined and victorious war against Duke Conrad of Zähringen. On 4 March, 1152, after having been designated by Conrad III as his successor, he was elected German king, unopposed, and crowned at Aachen on 9 March. Taking Charles the Great as his ideal of a German emperor, Frederick determined to expand his supremacy to its utmost limits. This explains his ecclesiastical policy. With astonishing firmness his bold spirit pursued the aims it had once marked out for itself. Though no scholar, Frederick surprises us by the clearness and cleverness of his speech, by his rapid comprehension and decision, and by his well-reasoned and logical policy. A born ruler, he considered it his duty to secure for his subjects the blessings of peace. The majesty of his personal appearance was combined with attractive kindliness. Though shrewd and calculating, he had at times fits of uncontrolled passion. However, he was sufficiently master of himself to restrain his anger if the object to be attained was endangered by an outburst. Such a man naturally excited the admiration and invited the confidence of his fellow-men.
The sense of national unity that grew out of the rivalries existing in the crusading armies found in him an ideal for its enthusiasm. In public opinion Frederick found the support which was lacking to his predecessors, Lothair and Conrad. The German people loved their king, who soon after his coronation visited the various parts of his realm and manfully exerted himself to establish internal peace. There was no reason why the secular princes of his empire should oppose the newly chosen king; his naturally conservative mind knew how to deal with existing forces. Of the princes, whose power was already approaching sovereignty, he demanded only respect for the existing order. He sought also to unite the interests of the German princes, especially those of the House of Guelph with the interests of the empire. The Gregorian, hierarchical party in Germany was in a state of complete dissolution. From the bishops Frederick had no reason to fear radical opposition to his policy towards the Church, dissatisfaction with the papal administration in Germany being then widespread. He succeeded in recovering the influence formerly exercised by the German king in the selection of bishops. Many powerful men were at that time to be found among the German clergy, prominent among them being the provost of Hildesheim, Rainald von Dassel, consecrated Archbishop of Cologne in May, 1156, and made chancellor of the empire. For eleven years he was the most faithful counsellor of Frederick. Rainald was a formidable opponent of the papacy; in him the bishop almost wholly disappears in the statesman. Similar to Frederick in character, he vigorously supported the anti-hierarchical policy of the emperor. Another prelate, also a stanch supporter of the king, was Wichmann, Archbishop of Magdeburg, more of a soldier than a bishop, and uncanonically promoted from the See of Zeitz to the Archbishopric of Magdeburg. Thus assisted by the various estates of the empire, Frederick sought to make the power of the crown as independent as possible. This he did by vigorously furthering the interests of his ancestral house. The administrators of his family property, the ministeriales, were not only managers of great estates, but at the same time an ever-ready body of warriors. The negotiations between the king and the pope concerning the appointment to the See of Magdeburg revealed for the first time a radical difference between the policies of the Church and the State. During these stormy controversies, forerunners of the approaching tempest, Frederick was strengthened in his views regarding the superiority of the royal over the papal power, chiefly through intercourse with the leading jurists of the University of Bologna. The conception of the dignity of the Roman emperor placed before him by these men confirmed him in his claims to the supremacy of the German kings over the Church, which he based upon the rights exercised by them during the Carlovingian period. The whole internal and external policy of Frederick was controlled by the idea of restoring the ancient imperium mundi. In Northern Italy, where many prosperous communes had acquired independence, the former imperial suzerainty had passed away. Frederick failed to see that in these cities a new political factor was developing, and underrated the powers of resistance of these free municipal republics. Concerned only with immediate advantages, he sought to recover the regalia (income from vacant sees and benefices), which the cities had gradually usurped, and to utilize them in pursuing his imperial policy. The conduct of Frederick in Northern Italy and the mistaken concept of the relations between Church and State could not fail to bring about a conflict with the papacy. In this conflict for supremacy in Northern Italy, the pope was forced to prove that he was able to defend the position of equality with the king, which the papal see had acquired, and in this way to gain a complete victory over the emperor. The king, a deeply religious man, was, indeed, convinced that the secular and ecclesiastical power should co-operate with each other, but he made it clear that even the pope should respect in him the imperial lord. If Frederick became master of Italy, the pope would have to acknowledge this supremacy. In the beginning, it seemed probable that Frederick would triumph. The pope needed German help. Threatened by the Normans from without, he was not even secure in his own city, which governed itself through a senate elected by popular vote and tolerated the revolutionary Arnold of Brescia within its walls. It was in these circumstances that the Treaty of Constance was signed between the pope and the king (March, 1153). This treaty was aimed against the enemies of the pope both in Rome and Southern Italy. In return the pope promised to crown Frederick emperor and to help him against his enemies.
In October, 1154, Frederick began his march Romewards. Owing to the weakness of his army, the king did not succeed at this time in subjecting to his power Northern Italy and the rebellious city of Milan. In 1155 he went on with his army to Rome, where he met the newly elected Pope Adrian IV, who maintained himself in Rome with difficulty and was anxiously awaiting the arrival of the German king. Frederick could not establish permanent order in Rome. The Treaty of Constance, promising the pope help against the Romans and Normans, was therefore not carried out. In On 18 June, 1155, after having delivered Arnold of Brescia into the pope's hands, Frederick was crowned as Roman emperor in spite of the opposition of the rebellious Romans. In Southern, as in Northern, Italy Frederick made little progress during this Italian expedition. During the years 1155-1158, Frederick reached the height of his power, and energetically safeguarded the tranquillity of his realm. The difficult Bavarian question, replete with imminent danger of war, was successfully settled; Henry Jasomirgott surrendered Bavaria to Henry the Lion and in return received Austria as an independent duchy, a step that was pregnant with consequences for the future of Germany. Frederick's policy was also successful along the eastern and western boundaries of his empire. His suzerainty in Burgundy was, in the main, re-established, after Frederick, with the consent of the Curia, had separated from Adela von Bohburg, and married Beatrice, the heiress of Burgundy. On his eastern frontier, he succeeded more and more in Germanizing and Christianizing the local tribes. In this respect, Henry the Lion was the chief pioneer of the future imperial policy. Frederick maintained amicable relations with Denmark, Poland, and Hungary. Impelled by his proud consciousness of authority, which found expression at the Diet of Würzburg (1157), Frederick undertook a second Italian campaign in 1158. In the meantime, conditions had changed in Italy; the pope, from being an opponent of the Normans, had become their ally. The friendly relations between the pope and emperor had suffered a shock after the Diet of Besançon (1157). On that occasion the papal legate had called the imperial dignity a benefice (beneficium) of the popes. The expression was ambiguous, since the Latin word beneficium might mean either a personal benefit or a feudal concession. There is no doubt, however, that the indignant German princes were right in understanding it to be an assertion of the superiority of the popes over the emperors. In sharp denial of this claim, Frederick defended his imperial sovereignty. The relations between pope and emperor became more strained. Pope Adrian was considering the excommunication of the emperor, when his death relieved the existing tension. Relying on his own resources, Frederick now began another campaign against the cities of Northern Italy. Milan succumbed after a short siege (7 Sept., 1158). At the Diet of Roncaglia the emperor undertook to define with precision the rights of the empire as against its subject rulers and cities, also to restore the earlier strong suzerainty by the appointment of imperial officials (podestà) in the North Italian cities. His intention was to establish peace, but the Lombards failed to understand this and openly rebelled. During his war with the city of Cremona occurred the disputed papal election of 1159. As supreme protector of Christendom, Frederick claimed the right to decide this quarrel. Of course, had he been able to enforce his claims it would have been a proof of the supremacy of the empire. The Synod of Pavia, assembled by Frederick in Feb., 1160, decided in favour of Victor IV. Thereupon, as Victor's protector, Frederick undertook to win over to the cause of this antipope the other rulers of Europe. Milan, in the meantime, had surrendered (March, 1162) and met with a fearful castigation.
The successes of the emperor excited the envy of the other European rulers. Pope Alexander III, animated with the spirit of Gregory VII, refused to acknowledge the imperial supremacy. Around the pope gathered all the enemies of Frederick. The universal papal power was destined to triumph over the idea of a universal imperial power. The Western rulers were determined to resist every attempt to re-establish the imperial hegemony in the West. Frederick was again left to his own resources and, after a short sojourn in Germany, undertook a new expedition to Italy (1163). For a time the death of the antipope, Victor IV, gave rise to hopes of a reconciliation between Frederick and Alexander III, but soon the emperor recognized another antipope, Paschal III. At the same time an anti-imperial alliance, the Lombard League, was formed by the cities of Verona, Vicenza, and Padua; it was joined by Venice, Constantinople, and Sicily. Internal troubles caused by the schism prevented the emperor from coping successfully with the famous League. Some of the German clergy, moreover, had espoused the cause of Alexander III, and Frederick was unable to overcome their opposition. Nevertheless, he again left Germany (1166), marched through the disaffected cities of Northern Italy, and accompanied by the antipope, entered Rome. There a deadly fever destroyed his army, while behind him the Lombard insurrection assumed more dangerous proportions. Lengthy negotiations followed, and the emperor again attempted to overthrow the coalition of the League and Pope Alexander (1174). The great battle of Legnano (29 May, 1176) destroyed the imperial hopes, and left Frederick willing to enter on negotiations for peace. The most important result of the ensuing treaty of Venice (1177) was the failure of the emperor to establish his supremacy over the pope; and in acknowledging the complete equality of Alexander, whom he now recognized as pope, Frederick confessed the defeat of the imperial pretensions.
While Frederick was fighting in Northern Italy, the head of the Guelphs, Henry the Lion, had refused to give him armed assistance. Now he openly rebelled against Frederick. The emperor overthrew Henry, and henceforth aimed at impeding the growth of his powerful vassals by dividing the dukedoms as much as possible. Bavaria, without Styria however, was at this time granted to the Guelph house of Wittelsbach, which act naturally revived the feud between the Houses of Guelph and Hohenstaufen.
The Treaty of Constance (25 June, 1183) between Frederick and the Lombards deprived the pope of his important ally, the combined cities of Northern Italy. Shortly afterwards, Frederick's son Henry married Constance, the Norman princess of Sicily. The papacy was now threatened both from the north and the south. Friendly relations between the pope and the emperor were also endangered by complaints about the exercise of the Jus spolii and the collection of the tithes by laymen. The coronation of Frederick's son Henry as King of Italy (27 Jan., 1186) led to an open rupture. The political weakness of the papacy was offset to some extent by the fact that Philipp von Heinsberg, Archbishop of Cologne and a powerful prince, became the champion of the pope. By skilful management and with the aid of a majority of the German bishops Frederick evaded the threatening peril.
The death of Urban III and the election of Gregory VIII brought about a change in the dealings of the Curia with the empire, owing chiefly to the gloomy reports from the Holy Land.
At the Diet of Mainz in 1188, Frederick took the cross, and on 11 May, 1189, started for Palestine. On 10 June, 1190, he met with a sudden death while crossing the River Saleph in Asia Minor."