Here's an article I wrote on Islam and the Crusades several years ago:
“How dreadful are the curses which Mohammedanism lays on its votaries! Besides the fanatical frenzy, which is as dangerous in a man as hydrophobia in a dog, there is this fearful fatalistic apathy. The effects are apparent in many countries. Improvident habits, slovenly systems of agriculture, sluggish methods of commerce, and insecurity of property exist wherever the followers of the Prophet rule or live. A degraded sensualism deprives this life of its grace and refinement; the next of its dignity and sanctity.” “The fact that in Mohammedan law every woman must belong to some man as his absolute property, either as a child, a wife, or a concubine, must delay the final extinction of slavery until the faith of Islam has ceased to be a great power among men.” “Individual Moslems may show splendid qualities– but the influence of the religion paralyses the social development of those who follow it. No stronger retrograde force exists in the world. Far from being moribund, Mohammedanism is a militant and proselytizing faith. It has already spread throughout Central Africa, raising fearless warriors at every step; and were it not that Christianity is sheltered in the strong arms of science, the science against which it had vainly struggled, the civilization of modern Europe might fall, as fell the civilization of ancient Rome.” –Sir Winston Churchill (The River War, first edition, Vol. II, pages 248– 50).
Muhammad was born in 570 AD in the Arabian city of Mecca (present-day Saudi Arabia). He was orphaned at an early age and raised by his uncle. He worked primarily as a merchant until age 40, when he claimed to have been visited by the angel Gabriel and received his first revelation from God. Three years later, he began to preach these revelations publicly. Initially, he didn't gain many followers and was generally treated with hostility. Eventually, he and his small band of followers were forced to leave Mecca for their own safety and relocate to Medina. There, he gained many Jewish followers who converted to Islam. Soon, he would seek revenge on Mecca for expelling him.
The Battle of Badr in 624 marked the first major battle between the Muslims and the Meccans, which ended in a decisive victory for Muhammad. The two forces would engage in several more battles over the years, which eventually culminated in a 10-year peace treaty, only to be broken in two years by Muhammad, and Mecca was conquered without a fight. The fall of one of the richest and most powerful cities in Arabia marked a shift in power and the rise of Islam. Meanwhile, the alliance with the Jewish tribes began to break down, as many Jews would not accept Muhammad as a prophet. After the Battle of the Trench in 627, Muhammad accused the Jews of treachery, so the men were beheaded and the women and children were sold as slaves. Muhammad discovered that it was far easier to spread his religion through force than through peace. Soon after his conquest of Mecca, he conquered the majority of Arabia in just two years. It is of interest to note that the same black flag that Muhammad flew in his time is the same black flag that Jihadists use today, including ISIS.
In the last ten years of his life, he ordered 65 military campaigns alone. Before his death in 632, his final words were said to have been "I was ordered to fight all men until they say, 'There is no God but Allah'". His followers were quick to continue where he had left off. Starting with what is present-day Iraq, Islam began to systematically conquer the entire Middle East. By 700 AD, they had conquered half the territory that had previously belonged to Christendom. From there, Islam set its sights on North Africa. In Alexandra, Egypt, philosopher John Philoponus tried to save the famous Alexandrian library from the Muslim conquerors, but Caliph ‘Umar had it destroyed, saying the Qur’an was sufficient, because those books agreeing with it are useless and those disagreeing are pernicious. After three forays into North Africa, it was finally conquered, and it remains a Muslim stronghold to this day.
A mere 80 years after Muhammad's death, Islam had spread as far east as China and the Indian Ocean and as far west as Morocco. It then spread into Europe through the Iberian Peninsula and into Spain and southern Italy, as well as many major Mediterranean islands, including Sicily, Corsica, Cyprus, Rhodes, Crete, Malta, and Sardinia. On April 30, 711, Muslim troops under the command of Tariq ibn Ziyad crossed the Straights of Gibraltar and landed on mainland Europe for the first time. The invasion took everyone in Spain completely by surprise. Within eight short years, the Muslims had occupied most of Spain. As part of their subjugation, the Spanish were forced to hand over 100 white virgins a year to the Muslims to be used in their harems.
The first Muslim invasion of Sicily took place in 652 but failed, as did repeated attempts in 667 and 720. Between failed attempts and a civil war among the Muslims, it took them 70 years to finally succeed. After the fall of Sicily, they crossed into southern Italy. Rome was pillaged twice, and the Pope was forced to pay a huge tribute. Several major Mediterranean islands were also conquered, including Cyprus, Rhodes, Sardinia, Majorca, Crete, and Malta. These islands became of strategic importance to Muslim fleets.
Pushing the Muslims out of Europe was no easy task. The Reconquista, which means reconquest, was a slow and long process lasting 750 years. The Reconquista began with the first Christian victory at the Battle of Covadonga in 722, and lasted until 1492 with the fall of the last Muslim stronghold during the Grenada War. The Reconquista would prove to be a source of encouragement for another Christian reconquest, the Crusades.