Many people, including historians, now believe that the Crusades were an unjustified series of attacks on Muslim countries by Christian Europe. In reality, Islamic Empires had taken more than two thirds of the Christian world by the 11th century and had murdered, forcibly converted, and enslaved thousands of Christians. The Middle East, North Africa, and parts of Spain, Asia Minor, and Southern Europe had been violently conquered. Another common misconception is that the Crusades were all about money, but really they put the participating nations in severe financial debt after it was over. 

However, the Christian Crusaders did commit wrongful acts, and instead of trying to convert Muslim civilians, they usually just killed them (which was common practice in medieval warfare). Of course, Muslim armies did the same with Christian civilians, probably at a larger scale. 

In 1096, Pope Urban II sent out a call for men across Europe to embark on a mission to take back the Holy Land from the Muslims, starting the First Crusade (1096-1099). The initial wave of men sent were peasants who had no professional training, and never even made it to the enemy because they ran out of provisions. The second wave was made up of professional knights, and in 1097 the Crusaders took Nicea. However, the next winter, there was widespread hunger and desertion. 

In 1098, the Crusaders entered Antioch, but were quickly surrounded by a large Muslim force. The Christians started digging, looking for the Holy Spear, which was thought to be hidden somewhere inside the city. Eventually finding this Lance, they took this as a sign from God and rushed out of the city to face the Muslims while carrying the Spear. Caught off guard, the Muslims were routed, and the Crusaders took Antioch. 

The Crusader army started a siege of Jerusalem in 1099, taking the city after the English arrived with siege equipment. The Crusaders massacred most of the Muslim inhabitants, and established four Crusaders states: Antioch, Edessa, Tripoli, and Jerusalem. In the Second Crusade (1147-1149) Crusaders attempted to take back Jerusalem and Edessa, which had been conquered by the Muslims, but were unsuccessful. 

During the Third Crusade (1189-1192), Muslims united their territory and army under a Sultan, so Holy Roman Emperor Frederick Barbarossa, King Phillip Augustus of France, and King Richard Lionheart of England prepared a force. Byzantine Emperor Isaac II was suspicious of Emperor Frederick because the Holy Roman Empire was an ally with the Normans, who were the Byzantine’s enemy. 

Emperor Isaac II made a deal with the Muslims to not attack them since he thought the Westerners were trying to conquer Byzantium. After the German and French armies mostly went home, Richard Lionheart, possibly the best military mind of the Middle Ages, took Cyprus by himself. When the French army arrived, Crusaders were able to recapture Tripoli, Antioch, Tyre, Jaffa, and Jerusalem. 

During the Fourth Crusade (1201-1204), the Crusaders got sidetracked when they tried to install Alexius as Emperor in Constantinople. Alexius had promised them wealth, but when the people heard that he was becoming Emperor, they were unhappy. When the Crusaders realized they weren’t going to be able to make Alexius emperor, (which meant that they wouldn’t get their money) they started a siege of Constantinople. The Crusaders took the city, robbed people of their belongings and stripped gold plates and sacraments from Cathedrals. Eventually, they murdered and raped civilians, and even burnt most of the city to the ground. 

Thousands of civilians were murdered and the Westerners put in a puppet government called the Latin Empire, which would rule for 50 years until the Byzantines took power again. After the First Crusade, the Holy Land switched sides multiple times. Notably, King Baldwin IV of Jerusalem single-handley kept it for the Christians until his death in 1185. In 1213, Pope Innocent III ordered another Crusade, and proclaimed that this time the Crusader’s personal debts would be paid for by the Church. 

Holy Roman Emperor Frederick II (r. 1220-1250) arrived with a tremendous number of men to Egypt, where Crusaders took the port city of Damietta after a siege in 1219. They even tried to convert the Sultan to Christianity. In 1221 Muslims besieged Damietta, and made a deal with the Crusaders to leave Egypt in exchange for the true Cross, but when the Christians left the Muslims didn’t give them the Cross. 

This whole time, Emperor Frederick II had not been helping, so when he delayed again, the Pope excommunicated him. Yet, Frederick went to the Holy Land regardless, even though no one was assisting him due to his excommunication. Frederick then made a deal with the Muslims to give him Jerusalem, but leave it unfortified, so he could report to the Pope that he had “conquered” the city. Shortly after the bargain was made, the Muslims entered the undefended Jerusalem and massacred the Christian inhabitants. 

King Louis IX of France (r. 1226-1270) started a Crusade again in 1248 and took Damietta in 1249. The Crusaders had setbacks, though, and returned home in 1254. After the fall of Acre in 1291, the Crusades in the Holy Land largely ended. 

Most of the turbulent Crusades were unsuccessful and had a negative impact on Christian Europe. The Sack of Constantinople also had a long-term effect on the Byzantine Empire, which never fully recovered and fell in the 1400s. Although the Crusades mostly ended in the late 13th century after the Fall of Acre, there were Crusades in other locations after.