The Islamic Invasions of Europe refers to the repeated invasions and conquests of Europe by Muslim invaders from the 8th century to the 18th century, ultimately ending with the defeat of the United Islamic Caliphate at the Battle of Berlin and Battle of Moscow. It began with the Umayyad invasion of Hispania, and continued with the invasion of Gaul. Following these two events, Islamic expansion began to slow in western Europe, but increased rapidly in eastern Europe.
In the Grand War, the Umayyad Caliphate expanded into southern Europe, first defeating the Byzantine Empire in the late 8th century, and expanding into Sicily. Using southern Europe as a launch pad, the Umayyads fully conquered Byzantium in the 9th Century, though spared Rome.
The Christians responded to this "heathen invasion" by forming various coalitions and alliances to combat Islam, usually ending in failure for the greater part of 500 years. The Pope and religious elite called the Islamic invasions the "apocalypse" (as they also did with the later Mongol Invasion) to drum up support from frightened Christians.
Things slowed for a while after this, with only minor conquests in the 10th and 11th centuries. Among them were the Kingdom of Bulgaria, Serbia, and other unorganized regions in southern Europe. Following the Reconquete in the 12th century, northern Al-Andalus was broken up into the Emirate of Narbonnes and Parisian Kingdom, which were at odds with each other, slowing western expansion. However, in 1122, the Parisian Kingdom crossed the English Channel and devastated the warring English kingdoms, uniting them for the first time under its rule.
Later, all of Italy fell, the Holy Roman Empire was nearly destroyed, Russia was not totally defeated but was reduced to a tributary state, and Poland was conquered. Repeated invasions were attempted against central and northern Europe, but the Mongols nearly destroyed the Caliphate through their invasions and eventually it was weakened so severely that almost every further invasion failed, until Islamic rule was confined totally to Iberia and the Balkan Peninsula.