|Commanders and leaders|
| Atticus I || Mojmir I of Moravia †
The Moravian War was a conflict beginning in 853 that lasted until 856 between the Carolingian Union and the rebellious Moravians. Interrupting the First Viking War, the Moravian War was put down fairly quickly to allow the Franks and Byzantines to return to the pressing Viking War, which was entering its second decade by the conclusion of the Moravian War. The war resulted in a Frankish victory and the death of Mojmir of Moravia.
The Moravians had been a part of the Frankish Empire, albeit culturally different. While they had seemingly accepted Frankish rule, the Moravians continued to see themselves as Moravian rather than Frankish citizens. In OTL, Mojmir I of Moravia rebelled when the Franks fell into civil war. However, due to the Frankish Civil War not occurring in this timeline, Mojmir waited until the year 849, during which the Battles of Aachen were taking place, to rebel against the Franks. The rebellion brought minimal resistance in the area, allowing Mojmir to continue ruling Great Moravia.
In 853, seeing that the Franks were still distracted with the First Viking War, Mojmir decided to attempt to claim more territory from the Frankish Empire. He invaded the Frankish Empire at some point in 853, requiring the First Viking War to be put on hold. Atticus I of the Frankish and Eastern Roman Empires led several tagmata into Eastern Francia to prevent the Moravians from gaining any more territory. The Franks and Byzantines pushed into Moravian lands in 854.
The war in 854 was a wild goose chase as Mojmir and his son, Rastislav, became targets for the Byzantine and Frankish invasions. The rebellion met its end in 855 when Rastislav's ring fortress was invaded. Rastislav was killed in the invasion. According to many accounts by Moravian prisoners, Mojmir had died a few months before the invasion of Rastislav's ring fortress. Nevertheless, the Moravian War was concluded following the death of Rastislav and the loss of Mojmir, leading to Francia's annexation of Great Moravia.
Following the conclusion of the Moravian War, the lands that had belonged to Great Moravia became the Duchy of Bohemia. Personally overseen by Atticus, the creation of this Duchy led to the assimilation of the Moravians into the Frankish Empire. While minor rebellions sporadically appeared in the area, they were quickly put down by the Franks. The war was seen as an example to other subkingdoms and duchies considering rebellion.
Moravia was relatively quiet until the Bulgar War in 884, when the Franks invaded Bulgaria from the Duchy of Bohemia.