After the Investiture Controversy of the 1170s-1180s, the power of the King in Germany was greatly weakened. Internal revolts and the lack of strong kings had allowed feudalism to spread without the monarchy being able to keep control of it. The agricultural expansion of the late tenth century in Germany had increased the wealth of the princes and counts, and during the controversy they had begun to encroach on the crown lands and prerogatives, such as hospitality dues, and advocacies. These latter were the secular and military administration of clerical estates in German territory. This allowed German nobles to take over monasteries for their own benefit and acquire clerical allies. As well, the nobles took advantage of urban growth in the duchies to make new cities their protectorates. With a more powerful and wealthy territorial base, the dukes' power vis-a-vis the king was much increased. As regards Italy, at the end of the Investiture Controversy, the German monarch's power had all but evaporated. North Italian bishops who supported the King were unable to maintain power over the burgeoning and increasingly liberated cities, which were often papal in sympathy.
During the period of the last Salian King Henry IV (r. 1056-1106) and Henry V (r. 1106-1126), two key ducal families emerged in Germany. They were the Welf (Geulf) of Bavaria, and the Hohenstaufen (Ghibelline) of Swabia. The Welfs were pro-papal, and were behind most of the noble revolts during 1100-1126, along with the western archbishops. The Hohenstaufens of Swabia, on the other hand, were the one great family upon whom the German monarch could rely. Problems emerged in 1126, when Henry died with no heir. He had nominated Frederick of Swabia, and Hohenstaufen, but the noble, pro-clerical electors instead chose Lothaire of Saxony (r. 1126-1137), assuming that he was weaker and therefore more malleable, especially as he too had no son and no dynasty would emerge. When Frederick was not allowed access to Henry's lands, he revolted. This revolt was put down, but the Welf-Hohenstaufen rivalry was by this time spreading into north and central Italy, with different cities supporting one or the other family. As he had received Welf support, Lothaire married his daughter to the Duke of Bavaria, Henry the Proud. Any male issue would thus become Duke of Saxony and Bavaria, and this alarmed the other nobles who did not want a supreme monarch. Thus, when Lothaire died in 1138, the noble electors passed over Henry the Lion and chose Conrad III of the Hohenstaufens, who ruled until 1152. He was a weak king, yet his principle achievement was to keep Henry the Lion out of Bavaria, though he did not prevent increasing Welf strength or the eastern duchies' expansion to the east outside of the crown's control. Conrad died while away on the second Crusade in Syria in 1152. He had nominated as his successor his brother Frederick of Swabia's son, Frederick.
Frederick I, "Barbarossa"--the red-bearded--was the most important twelfth- century German king. He sought to revive power of the German monarchy both at home as well as in Italy. He thus had to develop policies towards 1) Germany and its nobles; 2) the Italian cities, and 3) the Papacy.
Domestically, Frederick I recognized that the greatest challenge to royal authority were the allodial counts--those who had acquired their lands and power by other than feudal means. These had to be linked to the crown legally and contractually. Basically, Frederick wanted to rule as a powerful monarch based on feudal ties. Thus, in the 1150s, he began with a disarming policy. First, he favored the growth of towns, as centers of royal administration and monitoring of the crown domain. This allowed him to build the demesne back up, and conveyed to him revenues, as urban centers began to exert control over the rural surroundings. Directly regarding the rising noble classes, Frederick opted not to challenge their usurpations. Instead, he sold them charters, legitimizing their illegal seizures of power and lands. The German nobles were quite ready to buy legitimacy in such a way, and more cash came to the crown. Nobles were also required to provide troops for royal campaigns. Frederick thus created feudal ties, to his benefit. He also attempted to reduce tensions with the Welf, allowing Henry the Lion control of Bavaria, opening the way for more eastern expansion.
Between 1158 and 1180, Frederick undertook six expeditions into Italy, either in support of or in order to discipline the pope. At this time northern and central Italy was dominated by independent cities--communes. In Rome, the commune was lead by Arnold of Brescia, considered heretical for his anti- Papal attitude and desire to secularize all Church property. From 1145 he had been able to keep popes out of Rome, so when Adrian IV came to the throne (1154- 1159), the Pope was ready to call on external support. Frederick was equally desirous of clipping the Italian communes' wings. By 1156, Frederick had defeated and executed Arnold, restoring the Popes to Rome, and had laid siege to and razed Tortona, an ally of the independence-minded Milan commune. In 1158, Frederick went south again, and forced Milan to recognize Imperial overlordship. At Roncaglia, he announced the revival of al imperial rights going back to Carolingian times. He was to have the power to appoint dukes and communal consuls, to collect tolls and hospitality dues, as well as to be the sole general arbiter in Lombard regions. Though he guaranteed Milan's territorial integrity, he returned in 1160-1162 to lay siege to the city. Ultimately he razed it with the aid of other conmunes Milan had oppressed in the past.
At this point the Hohenstaufen embrace started to worry other Italian towns and the papacy. In 1159 Adrian had died. Two papal claimants emerged. While Frederick called a council to appoint the pope, most European leaders supported his opponent, Alexander III, thinking that the German king no longer had the right to appoint pontiffs. By 1165 Alexander had been able to occupy Rome; Frederick returned to drive him out, and Alexander was forced to flee to the Normans. When the German army became infected with Malaria, Frederick called off the expedition to the south. Shortly thereafter, thirty-six Lombard region towns formed the Lombard League. Spurred on by Alexander, their goal was to prevent the German authority from suffocating their liberties. In 1174 Barbarossa came south yet again, yet without Welf contingents, his army was outnumbered by league troops. On 28 May 1176 the two sides met at Legnano, and the Italians scored a resounding victory. In 1177, Barbarossa was forced to recognize Alexander as the legitimate Pope, after which a six-year truce was made with the Lombard League. He then went north to fight the Welf Henry the Lion, who had deserted him before the battle. This further exhausted the German crown, and required Barbarossa to make concessions to the feudalized nobles, though he did remain the uncontested overlord. In 1183, by the Terms of the Peace of Constance, he was made to guarantee the independence of the Italian towns. Finally, Frederick undertook one last expedition to Italy. The Norman William II in Sicily was entangled with the Byzantines, and Pope Lucius II (1181-1185) wanted to restore amicable Papal-German relations. He approved a Sicilian-German alliance, which was secured by the marriage of William's daughter Constance to Frederick's son Henry VI. A few years later, Frederick turned the crown over to Henry and went on the Third Crusade, drowning in an Anatolian river in 1190.