Not to be confused with the series of OTL conflicts known as the Italian Wars.
The Italian Wars were a series of conflicts in the Italian province that began in 894 and lasted until 928. Fought between the newly consolidated Carolingian Empire and the various Italian states, the war began over a dispute between Pope Formosus and Emperor Christophorus I. The Italian Wars ultimately ended with the entire Italian province under Carolingian control and the Christian church in the pocket of the Carolingian Empire.
Italy had been a very volatile region following the fall of the Western Roman Empire. Even after the creation of the Papal States by Charlemagne and the strengthened relationship between the Frankish Empire and the Byzantine Empire, Italy was a battleground in politics and war alike. As the 9th century progressed, the actions of the Franks and Byzantines were not always supported by the Papacy. The Franks continued to attempt to subvert the cardinals in order to place a Frank on the Papal throne. The attempts remained in vain.
Pope Formosus was especially critical of the Franks and Byzantines, stating that the two entities were 'doomed to fall by God's hand'. The final straw, however, was the Magnam Europae charter, which completely unified the Carolingian Empire. Fearing that the Church's authority would be limited by such a strong government, Formosus attempted to dissolve the union. The Carolingians, in return, began to plot a coup that would usurp Formosus and place a member of the Carolingian Empire on the throne.
Invasion of the Papal States
Almost immediately after declaring war, the Carolingian Empire invaded the Papal States from Ravenna, Lombardy, and from the west Mediterranean. Surrounded on almost all sides, the Papal States were seemingly doomed from the start of the war. The resistance they met was minimal, even for an outnumbered enemy. The lack of resistance resulted in the invasion of Rome taking place less than a year after the start of the war. Rome itself was a much tougher opponent, with the seige lasting more than a month. By the time the Carolingian forces entered the city, they willingly handed Pope Formosus over to the Carolingian Empire to cease the bloodshed. Formosus was blinded and imprisoned, where he met his death that year due to the injuries from his blinding. The Carolingian Empire placed a cardinal partial to their cause in charge of the Christian Church. The cardinal assumed the name 'John IX'.
Though the seat of the Christian Church was taken, the Italian Wars were far from over.
Following the assumption of John IX to the papacy, the Italian nation of Spoleto sought retribution in the name of the Christian Church. While Formosus was not a popular Pope at all, the actions of the Carolingian Empire angered Spoleto, leading to a declaration of war. Along with Benevento, Spoleto invaded Ravenna and the former Papal States in the hopes of making it clear to the Carolingian Empire that the Christian Church did not belong to the Carolingian Empire. Spoleto was partially successful in its goals; it was able to disrupt the Carolingian Empire's control of the Papal States for a time by cutting off supply lines.
With the Carolingian Empire distracted by rebellions in the Papal States, the war with Benevento, and their supply lines cut by Spoleto, many military leaders considered withdrawing from the Papal States. Christophorus, however, remained adamant in his resolve to not only hold the Papal States, but also acquire Spoleto and Benevento. In 895, Spoleto's conquests in the Papal States were disrupted by the Carolingian Empire. Spoleto would suffer a two-year-long invasion before falling to the Carolingian Empire.