Though during the eighth century, the Carolingians had succeeded in building a large empire, by the ninth century, the entire edifice was coming apart at the seams. One reason for this coming apart is military related: previously, the Franks had employed knights, and their unique sort of fighting capabilities—those involving horse charges with lances—against their enemies; this was a shift from more traditional forms of combat and though it took a while to become adapted, around the 8th century, we do see the shift becoming normalized. However, the Knights’ style of fighting was of little use against Viking attacks, which utilized surprise attacks and boat-oriented warfare.
The second reason that the Carolingian collapse happens is dynastic luck. Like the Merovingian before them, the Carolingians divided up their empire among their male sons when the last ruler died. But, between the time of Pippen the short and Charlemagne, this fate was avoided for the Carolingians due to the contents of previous lectures (re the unification of the empire without bloodshed and civil war). However, by the time that Lewis the Pious dies, his male children, all of whom are still living at the time of his death, do not get along; so, needless to say, when the younger children are given kingdoms subservient to their older brother, conflict becomes inevitable. Additionally, thanks to Lewis early efforts in an attempt to secure the Carolingian Empire, he inadvertently paralyzes the empire by having everyone focus on the succession issue.
Unfortunately, things became even more complicated when Lewis new wife, Judith, produced another child, who history would call Charles the Bald. Judith demanded that Charles is given some sort of inheritance. Obviously, this does not sit well with Lewis other children, all of whom intensely dislike their step-mother. The result is a rivalry which paralyzes the empire further. All of this is something that the Carolingians cannot afford as the Viking attacks intensify; in fact, there is reasonable evidence to suggest that the Vikings knew of the Carolingian political strife, and choose to intensify their attacks in the 830-40s, precisely because of the political drama.
Conflicted was further fermented thanks to the Carolingian aristocracy, many of whom wanted to see a civil war break out. Because the Carolingian Empire had not expanded for a couple decades, the military skills of the aristocracy were left wanting; many clamored for new lands and titles, new legislative powers, but without conflict, this would be impossible. But if civil war broke out, then the skills of these nobles could be used, yes, against fellow Carolingians, but the end result for said members of the aristocracy would be such new powers if they played their cards right and waited until the proper moment to throw their weight behind a combatant.
In 830, Pippen takes the Carolingian army and marches against his father. The conflict had begun: the trigger? Lewis giving a chunk of land, which, strictly speaking, did not exclusively gives Charles control over, to Charles the Bald. The other children saw this as an affront and revolted against their father.
Pippen accuses Judith of adultery and has her locked up in a monastery. Eventually, even Lewis is imprisoned in a monastery by his sons. Lothar, the oldest of Lewis sons, puts into effect the division of the empire which Lewis had drawn up, that which makes him supreme ruler of the empire. But, Lothar is betrayed by his brothers who free their father, both of whom believe that by his release he will increase the size of their inheritance. In 831 Lewis the Pious is freed along with Judith but is paralyzed as to what he should do, settling instead just to have things return to the status-quo. And though Lewis does not punish his sons, nothing is resolved.
In 833 a new rebellion breaks out. The children of Ermengarde (didn’t spell that right) become angry with Lewis the Pious after he temporarily confiscates the province of Aquitaine, and lead an army against him, imprisons him in a monastery, where he remains in captivity for ten months. But the two younger children, decide to, once again, double-cross their older brother with the belief that they will be rewarded by having their inheritance increase in size. But, once more, Lewis is bewildered by these actions and is unable to either punish or reward.
So far, very little bloodshed had occurred—events, as professor Dalileader has said, amounted to throwing dad into a monastery every couple of years. But when Pippen dies and Lewis gives Pippen’s former land to Charles, no one is happy as Pippen had a male child who the other brothers believe should inherit Aquitaine. So, by the time Lewis the Pious dies in 840, the Carolingian Empire is primed for a civil war.
When civil war did break out, it was Lothar who moved first against Charles the Bald, who had indeed inherited Aquitaine; Charles attempts to forge an alliance with Lewis the German, the idea being that by aligning with together—Lewis the German against his blood-brother with his half-brother—he will keep Bavaria. Lewis the German, surprisingly, buts the argument and they join forces together against Emperor Lothar.
Both sides meet in battle but it is a stalemate, one which, nevertheless, favors Lewis the German and Charles the Bald, since they are simply trying to hold on to what they already have. In 842, the alliance against Lothar is cemented when the two brothers meet in person to swear loyalty to one another; these are called the ‘Documents of Strasburg’ and constitute some of the oldest documents that we have in Old French and Old German.
The civil war comes to an end in 843 as Lothar, Lewis, and Charles come to an agreement called the ‘Treaty of Verdun’. This treaty, the so-called ‘birth certificate of Europe’, divided the Carolingian Empire into roughly three equal parts: the Western most part, West Frankia, goes to Charles the Bald; the middle-most kingdom, goes to Emperor Lothar; while the Eastern-most part of the Carolingian world, or East Frankia, goes to Lewis the German. Of this arrangement, Lewis the German and Charles the Bald do very well since it is a deal more territory than they had at the start of the civil war. The division of this land corresponds roughly to the borders of modern France and Germany, with a middle part between the two which will be fought over for the next several centuries.
Additionally, the imperial title becomes an empty honorific—it confers no power on the holder. The result of this treaty would be that instead of Europe being ruled by a single power, it would be ruled by a series of kingdoms which would eventually become nation-states.
Due to the reality of having three Frankish kingdoms, the history of the Carolingian world increases in complexity. Part in due to how sometimes when a ruler died he would sub-divide his kingdom (as happens to Lothar’s middle kingdom once he dies) or how one kingdom would, on occasion, conquer a smaller kingdom, the history of the Carolingian world become hostile to one another as the territories each nurse their own ambitions and goals. None of this is much appreciated by Carolingian contemporaries who due to the intensifying Viking raids throughout the 850-70s, beg their lords to fight the Vikings instead of one another.
In the early 880s, some Carolingian contemporaries believe that it was possible for the Carolingian Empire to return to their former glory. This is because a large number or rulers died in quick succession throughout Europe, leaving Europe almost bereft of Carolingian rulers. There was, however, one king left whom, when he died, would leave behind one five-year old heir, Charles the Simple. But the Catholic Church does not want the imperial title to go to a minority and instead gives it to an East Frankia king by the name of Charles the Fat, who becomes emperor of all the territories which had once belonged to Charlemagne himself. Now that all power was once again consecrated in the hands of a single ruler, big things were expected of Charles the Fat, namely in returning the Carolingians to great power.
In 885, the Vikings besieged Paris, giving Charles his first major test. The ruler of Paris, a man who fights desperately against the siege, sneaks out of the city to beg Charles to come to their aid, and later returns to fight his way back into the city, will be disappointed, though; Charles does come to their aid, but it takes him several months and when he finally does arrive, he simply pays the Vikings the donageld and they leave the city, being properly bribed. After this, people began to lose faith not only in Charles the fat but in the Carolingians more generally.
(In Charles’s defense, however, he seems to have suffered from some sort of nervous disorder; he had at least one nervous breakdown and constantly battled migraines.)
Charles the Fat, though, lacks any children. The fear was that upon his death the Empire would collapse to civil war once again, and so the Frankish aristocrats bands together to depose Charles, who dies just one year later. The empire disintegrates. So bad is the Carolingian dynasty discredited, that in both West and East Frankia, the dynasty is done away with all-together; two new dynasties emerge—the Capuchins in West Frankia, which will become modern France, and the Otomian in East Frankia which will become the Kingdom of Germany.