Much more serious than this outbreak among the Lombards was the disaffection of Tassilo III, Duke of Bavaria, who resented Charles’ aim to turn a nominal suzerainty into an effective control. United closely to the Frankish ruler by a common descent from Charles Martel, Tassilo, whose family, the Agilolfings, had governed Bavaria for two hundred years, had no mind to sacrifice the autonomy of his people. Even under Pippin he had showed that he placed a very loose interpretation on the ties of vassalage which bound him to the Franks. After Charles’ accession he continued his policy of isolation, showing by his failure to render assistance in the campaign against the Lombards that he did not recognize any obligation to further the ambitious schemes of his overlord. During the revolt of Friuli he observed an attitude of neutrality, an act which, coming from a vassal, could signify only that the Duke of the Bavarians claimed an independent position. Such a claim Charles was in no mood to allow. In 780, during one of the intervals in the progress of the Saxon conquest, Charles, accompanied by his wife and his sons, Carloman and Louis, spent Christmas at Pavia, the Lombard capital, and in Easter, 781, visited Rome, where the royal children received baptism at Pope Hadrian’s hands, and were raised by the ecclesiastical ceremony of anointment to the royal dignity, Carloman taking the title of King of Italy, and his brother Louis, that of King of Aquitaine. During this stay at Rome, the relations of Tassilo to the King of the Franks were discussed by Charles and the Pope. The result was that a joint deputation was sent from both Charles and Hadrian to Bavaria to remind its ruler of his obligations as a vassal of the Frankish kingdom. Tassilo soon after appeared personally at Worms to renew the oath previously sworn to Pippin. Hostages were exchanged on both sides, but the tension continued. We find Tassilo, a few years later, in 787, sending representatives to Rome in order to secure the Pope as an intermediary to establish an agreement with Charles and put an end to the mutual irritation of both parties. The terms offered by the Bavarians were not regarded as acceptable by the representatives of Charles, and the Pope himself solemnly appealed to the Duke to fulfil his promises as a dependent ally and so avoid the evils of war.

After his return from Italy Charles held his court at Worms and summoned Tassilo before him as the first step in acknowledging the overlordship of the Frankish monarch. In the eyes of Charles, swift dealing with a disobedient vassal was all the more necessary, because Tassilo, by his marriage with the daughter of Desiderius, might easily make himself the center of a revival of pro-Lombard feeling in Italy. Three Frankish armies from different quarters invaded Bavaria, and Tassilo soon found himself forced by this display of superior strength to give up his dreams of independent power. He formally resigned his duchy and received it back again from Charles’ hands, at the same time taking an oath as vassal and giving hostages, among whom was his own son. But not long after this Tassilo, who complained openly that his position of dependence was insupportable, was charged by members of his people with intriguing with the Avars. He was accused of treachery, and was condemned to death by legal process. But the sentence was reduced by Charles’ intervention to imprisonment in a monastery. His wife and children met a like fate, and from this time on Bavaria was treated as Frankish territory. Like Saxony, it was divided into jurisdictions under counts and placed under the supreme military control of one superior official.

The overthrow of Bavaria as a separate power laid the foundation of a consolidated Germany, North and South, and, as in Middle Germany, there was the same system of counties and bishoprics. Unity was still far from being thoroughly realized, but that the germ of national consciousness was already present is proved by the readiness of the Bavarians, after the loss of their ruling duke and their autonomy, to coöperate with the Franks in resisting the attacks of the Avars.

Just at the time that the tension in Bavaria was reaching its acute stage, the situation in the Lombard Duchy of Benevento, whose Duke Arichis seemed to be taking his cue from Tassilo, demanded attention. There were no actual hostilities, for the presence of Charles in the duchy was enough to bring the turbulent Duke to reason. His position of vassalage was marked by a payment of an annual tribute of 7000 solidi. The duchy was mildly treated by Charles because it was useful as a buffer against the provinces of the Eastern Empire, with which his relations were far from being always friendly. The result was that the Beneventines played a double rôle, sometimes befriending the Greeks and rejecting the Frank overlordship, and on other occasions engaging in hostilities with their Southern neighbors, as allies of the Franks. There were a number of Frankish expeditions necessary to keep the Lombards of Benevento and their dukes in mind of their duty as a vassal state, and once there was a noteworthy failure of Frankish arms in 792, when the campaign they had begun in the territory of the duchy was abandoned.

Apart from the campaigns in Saxony, in Italy, and in Bavaria, necessary to the integrity of the Frankish empire, there were various frontier wars undertaken, not for the purpose of incorporating fresh territory, but rather to impress upon contiguous peoples the power and prestige of Frankish arms. The occupation of Bavaria brought Charles in contact with the Avars, and his control of Aquitaine gave him as near neighbors the Moslems of Spain, those enemies with whom his grandfather, Charles Martel, had tried conclusions on the historic field of Poictiers.

This defeat had been inflicted on the conquerors of Spain at a time when the Ommayad Caliphate ruled over a united Moslem world. But the great internal revolution had broken this unity in 750, eighteen years before the accession of Charles. The last Ommayad Caliph, Merwan, after the great battle of Mosul, had been obliged to flee from Damascus to Egypt and had there met his death. Shortly afterward eighty members of his house were massacred by treachery at a banquet. Only one of the family escaped, Abderahman, the son of Merwan, who, after many adventures, reached Morocco, and was there invited to assume the rule of Moslem Spain, where the jealousies of the Emirs, the lieutenants of the far-distant Caliph in the East, had produced an era of misgovernment and faction.

So began in 755 the Caliphate of Cordova, and with it the most brilliant period of Mohammedan rule in Spain. But Abderahman was not accepted as supreme head of the Spanish Moslems without active protest; the Eastern Caliphate of the Abbasides had many supporters in the peninsula, and it was to Charles that they appealed for aid in resisting the Ommayad house. Naturally, the internal disputes of the Spanish Moslems constituted by themselves no ground for Frankish intervention. But the appeal was reinforced by promises that various Spanish cities would open their gates if Charles would undertake to cross the Pyrenees with an adequate army. This offer was made to Charles by Moslem envoys, who appeared before him at Paderborn, where he was holding a formal assembly (placitum) of the Frankish host during the early course of the Saxon war. The prospects of valuable territorial acquisition prompted the ruler of the Franks to embark on this hazardous expedition. There is no proof whatsoever it was undertaken to aid, as a kind of crusade, the feeble kingdom of the Asturias, where the heirs of the Visigoths were still maintaining the Christian cause against the Moslems.

In the spring of 778 the Christian army in force, containing contingents of Lombards and Bavarians, as well as Franks, crossed the Pyrenees, part of it passing into what afterwards became the Kingdom of Navarre, while the second division moved along the Mediterranean coast. Both were to meet at Saragossa, but before the junction was made Charles laid siege to Pampeluna, which had previously belonged to the small Christian kingdom of the Asturias. The city was taken, and at Saragossa hostages were received to guarantee to the Franks the possession of certain towns between the Ebro and the Pyrenees. With this inconclusive result the aggressive part of the campaign ended. Probably Charles hesitated to penetrate further into the country after hearing that Abderahman had lately defeated an army of Berbers who had come over to Spain to help the cause of the Abbaside Caliph. It was now evident that the prospects of the opponents of the Ommayad house were anything but brilliant, and it must have seemed advisable for the Frankish army to withdraw from Spanish territory. Summer had already begun before Charles turned his face homeward, after leveling the walls of the city of Pampeluna to the ground to prevent its inhabitants from revolting against him.

It was during this retreat that the famous disaster befell the arms of Charles, to which literary history has given an importance beyond its real deserts. On the 15th of August, at Roncesvalles, while the main army was slowly winding its way among the defiles of the mountains, the Basques applied to the Franks the guerrilla tactics they had successfully used against all the invaders of Spain, Roman, Gothic, and Moslem in turn. They made a sudden attack on the rear guard, and this division of the Frankish army was utterly cut to pieces. Many of the closest followers of Charles here met their death, among them Roland, prefect of the march of Brittany, of whom we know nothing apart from this brief notice in the contemporary histories, but whose exploits were celebrated in popular legend, where, under the glamour of poetical description, he has come to occupy a place as a warrior and hero almost the equal of Hector.

The defeat remained unavenged, for it was realized that the pursuit of the Basques in their mountain fastnesses was impossible. This expedition into Spain not only accomplished little in the way of permanent conquest, but served to provoke the Moslems to successful reprisals extending over a series of years in the Southern part of Gaul. The country was harried by the invaders, and towns as important as Carcassonne and Narbonne were attacked and the country about them ravaged. Dissensions among the Moslems themselves brought a respite, and, aided by insurgents against the authority of the Cordovan Caliphate, the Frankish officers in Aquitaine later on extended the sphere of Frankish influence far into the Iberian peninsula. Before the end of Charles’ reign Navarre and Pampeluna were again occupied, and he could number Barcelona among the cities of his empire.