For six years (781–787) the name of Tassilo disappears from the chronicles, and we may conclude that he was for so long a fairly loyal subject of the Frankish kingdom, or rather perhaps that he committed no such open act of rebellion as to compel Charles, engrossed as he was during these years by the war with Widukind, to send any of his sorely needed Frankish warriors for the chastisement of his Bavarian vassal.

Moreover, the open enmity of the Saxons was not the only danger that at this time menaced the security of the Frankish throne. In the year 785, immediately after the baptism of Widukind, we have the following mysterious entry in the chronicles: “There was made in that same year on the other side of the Rhine a vast conspiracy of the eastern Franks against the king, of which it was proved that Count Hardrad was the author. But information thereof was speedily brought to the king, and by his shrewdness so mighty a conspiracy shortly collapsed without any great danger, the authors thereof being condemned, some to death, some to privation of sight, and some to deportation and exile.” Even the king’s life was aimed at by the conspirators, yet Einhard assures us that none of the conspirators were actually killed save three who drew their swords upon the officers who were sent to arrest them. The cause of this sudden outbreak of Austrasian jealousy and rage against the great Austrasian hero must remain a mystery. Some of the authorities seem to speak of it as a specially Thuringian conspiracy, and one attributes it to the refusal of a Thuringian chief to hand over his daughter to a Frankish suitor to whom she was betrothed. An attempt has been made to account for it as the last struggle of Thuringian independence, dismayed at seeing the Saxons on the north and the Bavarians on the south subjected to the all-mastering Frankish king. It seems, however, more probable that it was a personal, palace conspiracy. Possibly Einhard gives us the requisite clue when he attributes both this and a subsequent conspiracy to the cruelty of Charles’s queen Fastrada who “diverted her husband from the kindness and accustomed gentleness of his nature.”

Towards the end of 786 Charles again marched into Italy, where the not only independent but even hostile attitude of Arichis, Prince of Benevento called for his attention. Having spent his Christmas at Florence, and paid his devotions at the tombs of the Apostles in Rome, he proceeded southward (787), and on the confines of the Beneventan territory was met by Romwald, son of Arichis, with gifts and promises and entreaties that he would not enter his father’s territory. But Charles, says the chronicler, “thinking that he must deal very differently with an enterprise once begun, kept Romwald with him and marched with all his army to Capua, where he pitched his camp, and would have carried on the war from thence, unless the aforesaid duke had anticipated his intention by wholesome counsel. For leaving his capital, Benevento, he betook himself with all his followers to the seaport of Salerno, as being a more fortified city, and, sending an embassy, he offered both his sons to the king, promising that he would willingly obey all his commands. Listening to these prayers, and moved also by the fear of God, the king abstained from war; and keeping the younger son Grimwald as a hostage, sent the elder son back to his father. He, moreover, received eleven hostages from the rest of the nation, and sent ambassadors to strengthen the covenant of the prince and all the people of Benevento by oaths.” Thus had the Frankish king, without striking a blow, extended his dominion to the southernmost corner of Italy. It was, however, a precarious conquest; and the princes of Benevento were almost to the end of Charles’s reign either doubtful vassals or open enemies of the Frankish ruler.

Easter of 787 was spent by King Charles in Rome, and this visit, like that of five years before was followed by a further development of the contest between him and Duke Tassilo. Doubtless the hollow reconciliation of 782 had been followed by mutual suspicion and estrangement: and the Bavarian duke must have felt that, with the Saxon rebellion now apparently quelled, his turn for subjugation would come next. While the king was still in Rome, there appeared in that city two Bavarian envoys, Arno Bishop of Salzburg, and Huneric Abbot of Mond See, who besought the pope to mediate between Charles and their master. The pope, as before, expressed his hearty goodwill towards Tassilo, and an interview between king and envoys followed in his presence. But when Charles called upon the bishop and the abbot to state what guarantee their master had empowered them to give for the fulfilment, this time, of his often violated promises, they could only answer that they had no instructions on this head, being not plenipotentiaries on Tassilo’s behalf, only messengers whose duty it was to carry back to their master the propositions of the king and pontiff. Apparently, then, the duke had reverted to that old position of all but equality with the Frankish king which he took up twenty-four years before at the time of the great harisliz, and the solemnly plighted oaths sworn at Worms were to go for nothing. Hadrian was not less indignant than Charles at this exhibition of fickleness and bad faith, and appears to have visited his displeasure on the two churchmen-ambassadors themselves, telling them that they and their master were all liars together, and that they should all be visited by the papal anathema unless Tassilo kept the oaths which he had sworn to Charles and to Pippin. We have here one of the earliest instances of that use of ecclesiastical censures to enforce political claims which was so characteristic a feature of the Middle Ages.

The ambassadors returned to Bavaria empty-handed: and the king, recrossing the Alps, went to rejoin his wife, the hard and haughty Fastrada, at Worms. Probably her influence was not used to soften his temper towards the rebellious duke. A general assembly was called, to which the king rehearsed all the events of his Italian journey, concluding with the story of the abortive negotiations with Tassilo. By the advice probably of his nobles, one more embassy was sent to claim from the Bavarian the fulfilment of his promises and to summon him to the royal presence. On his refusal, Frankish invaders from three different points entered the devoted duchy. Italian Pippin from the South marched from Trient up the valley of the Adige and over the water-shed of the Inn; Charles himself crossed the Lech and entered Bavaria from the west by way of Augsburg. A little further to the north, near Ingoldstadt, came an army of Austrasian Franks, including not only Thuringians but even Saxons, so great was Charles’s confidence in that pacification of the country which, as after events showed, was then but half completed. Seeing himself thus surrounded, and also knowing that many of his own subjects would side with the invaders—for apparently to the ordinary Bavarian landowner the prospect of a distant lord paramount at Aachen or Quierzy was more acceptable than the reality of a present and stringent master on the banks of the Danube—Tassilo gave up the game, presented himself at Charles’s headquarters, handed over to him a stick, carved into some resemblance of a man, as a symbol of the land for which he did homage, and gave as a hostage his son Theodo, who for the last ten years had been associated with him as ruler of the duchy. Hostages, as usual, twelve in number, were given for Tassilo’s adherence to his freshly made promises, and at the same time the people of the land were in some way, the details of which are not disclosed, made parties to his oath of fidelity to Charles.

It is not easy to account for the harsh proceedings of the next year (788) after this apparent reconciliation of the vassal to his lord. Possibly something had come to light which justified Charles in the belief that Tassilo would never honestly accept the position of vassal from which he had so often endeavored to escape. An assembly was convened at Ingelheim, probably in the month of June. Tassilo, now helpless and unarmed, was summoned to appear before it, and was there accused, on the evidence of some of his own subjects who were loyal to Charles, of having opened negotiations with the barbarous Avars on the east after his last submission to the Frankish king. Liutberga, his Lombard queen, mindful of the old feud and of her father’s wrongs, was said to have been the ceaseless preacher of revenge. Even against the life of Charles, Tassilo was accused of having conspired, and when men spoke to him of the danger in which he thus placed his hostage-son, he is said to have answered: “Had I ten sons I would lose them all in this cause, since it were better for me to die than to live a vassal on such ignominious terms as I have sworn to.” Then the old accusation of the harisliz of 763 was brought up against him, and on this and other charges he was found guilty by the assembled nobles, Franks, and Bavarians, Lombards and Saxons, assembled from all parts of Charles’s realm, and by their united voice was adjudged worthy of death. This sentence, however, was commuted by “the most pious Charles, moved by compassion and the love of God and because he was his kinsman: and he obtained from his own servants and the servants of God [the nobles secular and religious] this favor, that he should not die. Then Tassilo, being asked by the most clement king what he wished, begged that he might have leave to assume the tonsure and enter a monastery, there to do penance for so many sins, that he might save his soul. Similarly his son Theodo was sentenced, tonsured, and sent into a monastery, and the few Bavarians who chose to remain in opposition to King Charles were banished.”

According to one authority, Tassilo, while accepting tranquilly the decree which consigned him for the rest of his days to the monotonous seclusion of a convent, begged that his long hair, the symbol of his Frankish or even Merovingian descent, might not be shorn off in public, in the sight of his Frankish compeers, his Bavarian followers and companions in arms, and this favor was granted him by the clemency of the king. He was sent at once to the monastery of St. Goar on the Rhine, and afterwards to the safer seclusion of Jumièges in Normandy. His sons and his daughters were also persuaded or compelled to enter various convents: his wife, scion of that unhappy race which seemed doomed to disaster in all its members, was either banished or like the rest of her family accepted the sentence of seclusion in the cloister. Once more does Tassilo appear upon the stage of history, when in the year 794 he was brought to the assembly at Frankfort (an assembly convened ostensibly for a purely theological purpose) and there “made his peace with the lord the king, renouncing all the power which he had once held in Bavaria and handing it over to the king.” It is suggested that the law had been somewhat strained by Tassilo’s condemnation in the assembly at Ingelheim and that this formal and professedly voluntary surrender of his rights was deemed necessary to perfect Charles’s title as ruler of Bavaria. After this event Tassilo vanishes from the scene, the year and place of his death being alike unrecorded by authentic history.

For the later history of Europe and especially of Germany, the deposition of Tassilo and the vindication of the imperilled Frankish supremacy over Bavaria were perhaps even more important than the perpetually recurring Saxon campaigns which fill so large a space in Charles’s annals. Sooner or later Saxon-land was almost certain to become Christian and civilized, and so to enter the Frankish orbit: but at Charles’s accession there seemed to be a great probability that Bavaria would turn her de facto independence into separation de jure from the Frankish realm. This would have caused a separation of the Germany of the future into two independent states, a kingdom of the North and a kingdom of the South, which, as we know, never actually took place in the Middle Ages.

With one more conspiracy, this time of a domestic character, the tale of treason is ended. In the year 792 (the year in which Charles had an Avar war and a Saxon rebellion on his hands at once, and made his abortive attempt to join the Danube and the Rhine by a canal),[45] there was added to all his other cares a rebellion headed by one of his own flesh and blood. His eldest son Pippin was apparently not born in wedlock, though his mother Himiltrud, after her son’s birth, probably became Charles’s lawfully wedded wife. This defect of legitimacy would not have been an insuperable bar to succession in a house which derived its chief glories from the illegitimate Charles Martel; but there was another and more fatal circumstance in the case of Charles’s firstborn. Though beautiful in face he was deformed, probably dwarfish in figure, an unsuitable person therefore to be presented to the assembled Frankish warriors as heir to his father’s kingdom. Thus Pippin, though to a certain extent maintaining his princely rank, and named next to his father in the litanies of the Church, seems to have been silently edged out from all hope of succeeding to any portion of that father’s power. Charles, the eldest son of Hildegard, was apparently recognized as principal heir. Carloman and Louis were taken to Rome in their infancy and anointed Kings of Italy and Aquitaine, while Pippin was left unnoticed. Perhaps even the imposition of the ancestral name of Pippin on the child Carloman was meant as a hint to his elder namesake that he would never be saluted as Pippin, King of the Franks.

This exclusion doubtless galled the firstborn; and to these wrongs of his, real or imaginary, appear to have been added some inflicted on him and on his friends and followers by the unloved Fastrada. Thus, while most of the other chroniclers can see in the conspiracy of Pippin only the unholy attempt of a bastard, like another Abimelech, to seize the royal power at the cost of the lives of all his legitimate brethren, the honest Einhard in the following passage of his annals puts a different color on the enterprise.