Western Roman Empire (Ethelred the Pious)

The Holy Roman Empire began with Charlemagne, King of the Franks, who was crowned Roman Emperor by the Pope in 800. Over the, the realm was divided and reunited repeatedly, but the Carolingian dynasty remained on the Imperial throne. In the later decades of the Ninth Century,  began to take their toll on the Empire's northern reaches.

From the conquest of England to the Robertian rebellion
The Viking conquest of England diverted Norse attacks on the Empire for a time. Many of Scandinavia's ambitious young men saw more opportunity in acquiring land in England than in raiding the Franks. The attacks that were made were rather small-scale. Sigfred, a Danish chieftain and early king of Denmark, attacked Paris in 885. But unlike OTL, he did so without the great leader, who was subduing the Saxons in Devon and the Welsh in Cornwall at the time. The Viking band that sailed up the Seine that year was a good deal smaller than in OTL, since England was drawing off so many of the Vikings' energies.

Odo, defender of Paris, drove the Danes off easily. Instead of bravely defeating a mighty army, he drove off a petty raiding party. So Odo never became a famous general, and never was elected king of the Western Franks.

So unlike OTL, the Empire continued under the Carolingians at least a little longer. The emperors in this era were:


 * Charles the Fat: 881-888
 * Louis the Wary:888-915: The disastrous Italian campaign that resulted in his blindness in OTL did not happen. He was ultimately killed in battle against the Magyars.
 * Charles the Simple: 915-932

During Charles the Simple's reign, Viking attacks ersumed after a 40-year lull. This time the raiders came from England in force beginning in the 820s. The new round of attacks tore the Carolingian empire apart at last. Protesting the lack of protection from the Emperor, Odo's brother Robert began his revolt. Ultimately he captured Charles, who died in prison.

Robert's descendants eventually assumed the title Kings of Neustria. In the wake of his rebellion, the wide Kingdom of Aquitaine was cut off from the core Frankish lands. The line of Roman Emperors continued unbroken in eastern Francia and the core Franconian region, comprising OTL Germany and a sizeable chunk of OTL France. The Duchy of Anguelenie (approximately OTL Normandy), founded by the Anglo-Norse invaders, became a vassal of the Empire, not of Neustria.