THE death of Louis the Pious and his clearly expressed last wishes secured the imperial dignity to Lothar. But the situation had not been defined with any precision. The last partition, decreed in 839, had made important alterations in the shares assigned to the three brothers. Now what Lothar hastened to claim was “the empire such as it had formerly been entrusted to him”, namely, the territorial power and the pre-eminent position secured to him by the Constitutio of 817, with his two brothers reduced to the position of vassal kinglets. To make good these claims Lothar had the support of the majority of the prelates, always faithful, in the main, to the principle of unity. But the great lay lords were guided only by considerations of self-interest. In a general way, each of the three brothers had on his side those who had already lived under his rule, and whom he had succeeded in winning over by grants of honors and benefices. Louis had thus secured the Germans, Bavarians, Thuringians and Saxons, and Charles the Neustrians, Burgundians, and such of the Aquitanians as had not espoused the cause of Pepin II. But it would be a mistake to see in the wars which followed the death of Louis the Pious a struggle between races. As a contemporary writes, “the combatants did not differ either in their weapons, their customs, or their race. They fought one another because they belonged to opposite camps, and these camps stood for nothing but coalitions of personal interests”.

Lothar received the news of his father’s death as he was on his way to Worms. He betook himself to Strasbourg, and in that town the oath of fealty was sworn to him by many of the magnates of ancient France who were still loyal to the Carolingian family and to the system of a united empire, being vaguely aware that this system would secure the predominance of the Austrasians from among whom Charles and Louis the Pious had drawn almost all the counts of their vast empire. But Louis the German, on his part, had occupied the country as far as the Rhine, and Charles the Bald was also making ready for the struggle. Lothar had not resolution enough to attack his two brothers one after the other and force them to accept the re-establishment of the Constitutio of 817. He first had an interview beyond the Rhine with Louis, concluding a truce with him until a forthcoming assembly should meet, at which the conditions of a permanent peace were to be discussed. Then he marched against Charles, many of the magnates of the district between the Seine and the Loire joining him, among others Gerard, Count of Paris, and Hilduin, Abbot of Saint-Denis. But Charles, being skillfully advised by Judith and other counselors, among them an illegitimate grandson of Charles the Great, the historian Nithard, opened negotiations and succeeded in obtaining terms which left him provisionally in possession of Aquitaine, Septimania, Provence and six counties between the Loire and the Seine. Lothar, besides, arranged to meet him at the palace of Attigny in the ensuing May, whither Louis the German was also summoned to arrange for a definitive peace.

The winter of 840-841 was spent by the three brothers in enlisting partisans and in gathering troops. But when spring came, Lothar neglected to go to Attigny. Only Louis and Charles met there. An alliance between these two, both equally threatened by the claims of their elder brother, was inevitable. Their armies made a junction in the district of Chalons-sur-Marne, while that of Lothar mustered in the Auxerrois. Louis and Charles marched together against the Emperor, proposing terms of agreement as they came, and sending embassy after embassy to exhort him “to restore peace to the Church of God”. Lothar was anxious to spin matters out, for he was expecting the arrival of Pepin II (who had declared for him) and of his contingent of Aquitanians, or at least of southern Aquitanians, for those of the centre and north were induced by Judith to join Charles the Bald. On 24 June, Pepin effected his junction with the Emperor. The latter now thought himself strong enough to wish for a battle. He sent a haughty message to his younger brothers, reminding them that “the imperial dignity had been committed to him, and that he would know how to fulfill the duties it laid upon him”. On the morning of the 25th, the fight began at Fontenoy in Puisaye, and a desperate struggle it proved. The centre of the imperial army, where Lothar appeared in person, stood firm at first against the troops of Louis the German. On the left wing the Aquitanians of Pepin II long held out, but Charles the Bald, reinforced by a body of Burgundians who had come up, under the command of Warin, Count of Macon, was victorious against the right wing, and his success involved the defeat of Lothar’s army. The number of the dead was very great; a chronicler puts it at 40,000. These figures are exaggerated, but it is plain that the imagination of contemporaries was vividly impressed by the carnage “wrought on that accursed day, which ought no longer to be counted in the year, which should be banished from the memory of men, and be forever deprived the light of the sun and of the beams of morning”, as the poet Angilbert says, adding that “the garments of the slain Frankish warriors whitened the plain as the birds usually do in autumn”. At the end of the ninth century, the Lotharingian chronicler, Regino of Prüm, echoes the tradition according to which the battle of Fontenoy decimated the Frankish nobility and left the Empire defenseless against the ravages of the Northmen.

In reality, the battle had not been decisive. Louis and Charles might see the Divine judgment in the issue of the fight, and cause the bishops of their faction to declare that the Almighty had given sentence in their favor, yet, as the annalist of Lobbes put it, “great carnage had taken place, but neither of the two adversaries had triumphed”. Lothar, who was stationed at Aix-la-Chapelle, was ready to carry on the struggle, and was seeking fresh partisans, even making appeal to the Danish pirates whom he settled in the island of Walcheren, while at the same time he was sending emissaries into Saxony, to stir up insurrections among the free or semi-free populations there (the frilingi and lazzi) against the nobility who were of Frankish origin. His two brothers having again separated, he attempted to re-open the struggle by marching in the first instance against Louis. He occupied Mayence, and awaited the attack of the Saxon army. But on learning that Charles, on his side, had collected troops and was marching upon Aix, Lothar quitted Mayence and fell back upon Worms. Then, in his turn, he took the offensive against his youngest brother and compelled him to give back as far as the banks of the Seine. But Charles took up a strong position in the neighborhood of Paris and Saint-Denis. Lothar dared not bring on a battle, so he fell back slowly upon Aix, which he had regained by the beginning of February, 842.

Treaty of Verdun

Meanwhile his two brothers drew their alliance closer, and Charles, with this object, had made an appeal to Louis. The latter went to Strasbourg, and there on 14 February, the two kings, surrounded by their men, had a memorable interview. After having addressed their followers gathered together in the palace of Strasbourg, and recalled to them the crimes of Lothar, who had not consented to recognize the judgment of God after his defeat at Fontenoy, but had persisted in causing confusion in the Christian world, they swore mutual friendship and loyal assistance to one another. Louis, as the elder, was the first to take the following oath in the Romance tongue, so as to be understood by his brother’s subjects : “For the love of God and for the Christian people, and our common salvation, so far as God gives me knowledge and power, I will defend my brother Charles with my aid and in everything, as one’s duty is in right to defend one’s brother, on condition that he shall do as much for me, and I will make no agreement with my brother Lothar which shall, with my consent, be to the prejudice of my brother Charles”. Thereupon Charles repeated the same formula in the Teutonic tongue used by his brother’s subjects. Finally, the two armies made the following declaration each in their own language: “If Louis (or Charles) observes the oath which he has sworn to his brother Charles (or Louis) and if Charles (or Louis) my lord, for his part, infringe his oath, if I am not able to dissuade him from it, neither I nor anyone whom I can hinder shall lend him support against Louis (or Charles)”. The two brothers then spent several days together at Strasbourg, prodigal of outward tokens of their amity, offering each other feasts and warlike sports, sleeping at night under each other’s roofs, spending their days together and settling their business in common. In the month of March they advanced against Lothar, and by way of Worms and Mayence reached Coblence, where the Emperor had collected his troops. His army, panic-stricken, disbanded without even attempting to defend the passage of the Moselle. Louis and Charles entered Aix, which Lothar abandoned, to make his way to Lyon through Burgundy. His two brothers followed him. Having reached Chalon-sur-Saone they received envoys from the Emperor acknowledging his offences against them, and proposing peace on condition that they granted him a third of the Empire, with some territorial addition...