The Carolingian civil war was a violent crisis over the succession to the Carolingian Empire following the death of Emperor Louis the Pious in June 840 and lasting until the Treaty of Verdun in August 843. Louis's eldest son, the emperor Lothar I, laid claim to an undivided empire, while his younger brothers Louis the German and Charles the Bald sought large kingdoms of their own on the basis of previous divisions planned by the late emperor. Their nephew, Pippin II, laid claim to Aquitaine.
After Louis the Pious's death, Lothar moved immediately to disregard the division of the empire and secure for himself his father's imperial position. He reached out to Pippin in Aquitaine for support against Charles. Not content with Bavaria alone, Louis the German occupied the Rhineland laying claim to all of Germania. The first military move of the budding civil war was Lothar's campaign that forced Louis from the Rhineland in August. It increased Lothar's prestige in the east, but ended in an armistice. Lothar then marched to the Seine in September, laying claim to Neustria, before reaching a truce with Charles.
The climax of the war was the spring of 841. Charles crossed the Seine and Lothar crossed the Rhine. After forcing Louis to retreat, Lothar turned to face Charles. On 13 May, while Charles and Lothar were manoeuvring, Louis defeated Lothar's occupying army in Alemannia at the battle of the Ries. He joined up with Charles in early June. At the same time, reinforcements from Aquitaine arrived in both camps. The battle of Fontenoy took place on 25 June. Lothar and Pippin were routed, but the battle was not decisive.
In August 841, Lothar attempted to cross the Rhine but was turned back by Louis. Charles invaded Aquitaine before reoccupying the lands east of the Seine. Lothar quickly reoccupied them, forcing Charles back beyond the Seine, but was unable to recreate the support in West Francia that he had formerly had. In early 842, Louis crossed the Rhine. He and Charles swore the Oaths of Strasbourg on 14 February before marching north. They met Lothar's army on the banks of the Moselle in March 842. Lothar retreated towards Burgundy, conceding the imperial capital of Aachen.
Following their success, Louis and Charles divided the empire between themselves, leaving Lothar only Italy. This prompted Lothar to seek a negotiated settlement. By June 842, a new tripartite division had been agreed in principle. During the subsequent truce, Charles took control of Aquitaine and Louis crushed a rebellion in Saxony, which Lothar had supported. The final negotiations, begun by 120 commissioners drawn from all sides in October, were delayed by the need to formally describe and inventory the empire. This was completed in July 843. In August, the three brothers signed the Treaty of Verdun ending the war.
Background
Beginning in 830, the reign of Louis the Pious was troubled by a series of revolts involving his sons. The first began in February 830, when the army mutinied on the eve of a campaign against Brittany. Lothar, ruling Italy, and his brother, King Pippin I of Aquitaine, sided with the rebellious nobles. Pippin deposed Louis during a meeting at Compiègne and imprisoned Louis's second wife, Judith, the mother of Charles the Bald. Lothar left Italy to take charge, but the rebellion had collapsed by February 831. In the end, all were forgiven.
The second rebellion broke out in 833, spurred by Louis's decision to deprive Pippin I of Aquitaine and bestow it on Charles. This time, Louis the German joined Lothar and Pippin. In the armed confrontation of the so-called Field of Lies, Louis was captured along with Judith and Charles. Lothar ruled the empire for the next ten months, until Louis the German rescued his father from captivity and restored him to his throne in February 834. Lothar, Pippin and Louis were permitted, however, to remain kings in Italy, Aquitaine and Bavaria, respectively.
In 837, the emperor created a kingdom for Charles between the Meuse and the Seine with Burgundy. In 838, he added to it a part of Neustria. When Pippin died later that year, Louis disinherited Pippin II and granted his kingdom to Charles. This was the first break from the Ordinatio Imperii of 817. In 839, a new division of the empire was made between Lothar and Charles with Louis retaining Bavaria. This prompted Louis to rebel. His father defeated him, but died shortly after.
Louis the Pious died on 20 June 840. According to Agnellus of Ravenna and Andreas of Bergamo, celestial portents presaged Louis the Pious's death. The former reports the division of the empire, but remarks that "with Louis dead, there was always war between the brothers, or there was but unstable peace." Andreas records that "dissension arose among these three brothers, with Louis and Charles on one side, and Lothar on the other."
Initial jockeying
Since his father had summoned him to Worms for early July, Lothar was in Italy preparing to cross the Alps when he received news of his father's death. According to the contemporary historian Nithard, he delayed his journey in order to find out "which way things would go before he crossed the Alps". On learning that he had strong support, he laid claim to "the whole empire", disregarding the partition plan of 839. Shortly before his death, Louis the Pious had sent the imperial sceptre and crown to his eldest son. This was the basis for his claim to the whole empire. His messengers threatened death to those who resisted his claims.
According to Nithard, "men were driven by greed and terror" to support one or another brother. Nithard himself joined Charles at Bourges in July. He may even have been the messenger who brought news of the emperor's death. As a result of his support for Charles, his lands were confiscated by Lothar. Thus, his portrayal of Lothar is negative throughout. The evidence of surviving charters, however, demonstrates that in the first two years of war Lothar was the most popular brother and his claims to the empire were taken seriously. Between the death of his father and the end of 841, he issued 22 charters, half of the confirmations requested by the recipients. This compares to five and seven charters for Louis and Charles, respectively.
On learning of the emperor's death, Charles sent messengers to Lothar in July to remind him of the 839 agreement and of his responsibilities as an elder brother and godfather. In response, Lothar asked Charles to "spare" their nephew, Pippin, whom Charles regarded as a rebel, "until he [Lothar] might have a chance to speak with him", intimating support for Pippin's claims. Pippin himself moved quickly to ingratiate himself with Lothar. Already on 29 July, he issued a charter dated to "the first imperial reign-year of Lothar".
Lothar–Louis standoff
Louis the German responded to the news of his father's death by gathering an army along the Rhine. Crossing the river, he marched to Worms, where he installed a garrison before proceeding to Saxony.
Lothar, meanwhile, had arrived at Strasbourg by July 24. In August, he held an assembly at Ingelheim. It was well attended by bishops from west of the Rhine, including from Charles's kingdom, but no bishops from Bavaria, Louis's stronghold, attended. The assembly agreed to the release and reinstatement of the deposed archbishop Ebbo of Reims, one of Lothar's strongest supporters.
Lothar made the first military move, launching an attack on Worms. After a skirmish, Louis's garrison withdrew. Lothar then crossed the Rhine at Mainz. There, on 13 August, he granted some fiscal land at Rémilly to the abbey of Saint Arnulf in Metz where his father was buried. Marching on Frankfurt, he was met en route by Louis, coming from Saxony with a large army. The two exchanged messages and prepared for battle. At the last moment, they reached an armistice and agreed to meet again at the same place on 11 November.
The standoff with Lothar increased Louis's prestige. He followed it up by securing the support of Alemannia, Franconia, Thuringia and Saxony. In Alemannia, he expelled the pro-Lotharian abbots of Saint Gall, Reichenau and Kempten and installed his own candidates. By February 841, he had also successfully removed Abbot Hraban from control of Fulda.
Contest for Neustria
Support for Lothar was high in the region between the Meuse and the Seine. At least one count, Odulf, did immediately defect. At the behest of his supporters in the region, Charles travelled from Bourges to Quierzy in August to shore up his position. He left his mother, Judith, in command at Bourges. When he was informed that Pippin II was preparing an assault on Bourges, he abruptly returned in time to surprise the Aquitanians and force their flight.
In late September, Lothar crossed the Meuse and stated his intention to reach the Seine. At this juncture, the abbot of Saint-Denis and the count of Paris threw their support to him, as did Lothar's cousin, Count Pippin of Vermandois. The monasteries of Faremoutiers, Saint-Maur-des-Fossés, Nesle-la-Reposte, Flavigny and Saint-Amand all recognized Lothar. Lothar re-established Ebbo in Reims. In October, he crossed the Seine into Neustria. His support extended into Brittany. His support was strongest on the coast and he controlled the port of Quentovic. In November, he met Charles at Orléans. Lothar agreed to a truce with Charles, which included a promise not to attack Louis. He recognized Charles's rule for the time being in Aquitaine, Septimania, Provence and a part of Neustria. The truce was to last until 8 May, when the two were to meet again at Attigny. According to Nithard, Lothar used the truce to woo supporters in Charles's realms, moving quickly towards Provence. As such, Charles's men regarded themselves as absolved of the oaths of Orléans almost immediately.
First winter
When Lothar did not show up for the 11 November meeting, Louis returned to Saxony. He held an assembly in Paderborn, in defiance of its bishop, Badurad, who was with Lothar, and expelled the bishop of Osnabrück, Goswin, another supporter of Lothar. He granted an estate at Empelde confiscated from the margrave Banzleib to the abbey of Corvey, whose abbot, Warin, supported him. He refused, however, to confirm the abbey's exemption from military service, since he expected to need it.
In late 840, Pippin II was able to install his preferred candidate, Rodulf, in the archbishopric of Bourges. Charles returned to Bourges to meet Pippin in January 841, but Pippin himself did not show, sending Bernard of Septimania in his stead. Charles's men ambushed Bernard at his approach, but he managed to escape. His men were killed or captured and his baggage seized. Frightened by the affair, Bernard promised to "deliver" Pippin to Charles.
From Bourges, Charles went to Le Mans to restore Bishop Aldric. At the same time, the Breton ruler Nominoe switched his allegiance from Lothar to Charles.
Spring 841
Opening moves
In late March 841, Charles began marching from Le Mans towards Paris, although the Seine was in flood. Lothar's Neustrian supporters, Count Gerald of Paris and Archbishop Guntbold of Rouen, made preparations to prevent his crossing by destroying bridges and boats. Near Rouen, however, Charles succeeded in requisitioning 28 merchant vessels. He sent messengers ahead, declaring that he was merely making good his rights, announcing an amnesty for all who supported him now and ordering all those loyal to Lothar to leave his kingdom. He affixed the cross on which the oaths of 839 had been sworn to his prow and crossed the river on 31 March. According to Nithard, Gerald and Guntbold watched the crossing before retreating. Charles could not pursue them because of delays in getting his horses across. He visited the monasteries of Saint-Denis and Saint-Germain-des-Prés but did not or could not enter Paris.
At the same time, Lothar, at the urging of Archbishop Otgar of Mainz and Count Adalbert of Metz, moved against Louis. According to Nithard, Otgar and Adalbert, who had only recently recovered from a long illness, nursed a personal hatred of Louis and wished to see him dead. Lothar managed to turn some of Louis supporters and secretly crossed the Rhine with a large army in April. Some of Louis's followers betrayed and attempted to capture him, but he escaped to Bavaria. Lothar then returned across the Rhine, leaving Adalbert in charge with the title of dux (commander) of Austrasia and ordering him to take oaths from the east Frankish nobility.
On 13 April, Charles the Bald left Sens intending to ambush Gerald and Guntbold in the Forest of Othe. They received a warning, however, and managed to escape. Having force-marched his army so far, Charles had to rest his men and animals at Troyes, where he spent Easter (15–18 April). Around the time he crossed the Seine, he informed his Aquitanian supporters of his intentions and instructed them to join him. Envoys from Judith met him at Troyes with treasure while she herself was preparing to march north with reinforcements. On 18 April at Troyes, Lothar's envoys warned Charles not to advance further, while Abbot Lupus of Ferrières urged Charles to seek "a bloodless victory". The next six weeks were characterized by manoeuvre warfare between Lothar and Charles.
Battle of the Ries
In April, Charles sent an urgent message to Louis in Bavaria. Unable with his small Bavarian army to confront head on the army of Adalbert guarding the road through Alemannia, Louis decided to cross the Danube and lead his enemies into the Ries. This was a region of small rivers and streams that flow into the Wörnitz, which in turn flows into the Danube. Louis's intention was probably to dissipate Adalbert's army in many separate river crossings, leaving him vulnerable to an ambush while buying himself time.
The armies met on Friday, 13 May. From contemporary descriptions, Adalbert crossed the Wörnitz to attack Louis. He was probably caught by surprise before his men could be ready for battle. The battle was a rout. Adalbert himself was killed in the fighting. Louis's Bavarians stripped the slain of their valuable arms and armour. Thereafter, they formed the elite nucleus of his growing army.
News of the battle of the Ries and of the death of Adalbert spread quickly. Nithard records that Charles's army rejoiced when they learned that Louis had broken out of Bavaria. Louis's march west took another three weeks and he arrived at Auxerre with his elite Bavarian army short of horses.