The First Crusade
After the Normans had settled in France and conquered England, both France and England, and also the Holy Roman Empire, were stronger than they had been since the time of Charlemagne. Their kings and queens began to think, as he
had, of reconquering the whole Mediterranean and recreating the Roman Empire. In particular, they wanted to take Jerusalem, the city of Jesus Christ, away from the Islamic Fatimids who were ruling it.
People were so enthusiastic that several groups set off for Jerusalem before the main group was organized. They believed that God would just knock down the walls of Jerusalem anyway as soon as they got there, so there was no need for fighting or weapons. Some of them didn't even take any money. Most of these groups found that traveling and fighting were harder than they had imagined, and most of them died on the way. One group decided it was too hard to get to Jerusalem to fight the Fatimids, and instead stopped in Germany to fight the Jews. Thousands of Jews were robbed and killed by these Crusaders, just because they were not Christians.
Finally in the fall of 1096 the main Crusade left for Jerusalem. They went by different routes, some by land and some by sea, to Constantinople. Here the Emperor Alexius was quite surprised to see them and not altogether pleased. Would this army try to take over his own empire? But he sent them on towards Jerusalem.
The Fatimids were still not worried, because they thought this was just a little army of Roman soldiers from Constantinople, who just wanted to fight a little in Syria.
Dome of the Rock mosque, Jerusalem
The Crusaders finally reached Jerusalem in May, 1098. They were surprised to see all the civilized things in the city of Jerusalem - the Dome of the Rock mosque, and hot baths, and advanced Islamic medicine.
The Crusaders taking Jerusalem
The Crusaders made many mistakes in their fighting. But the Fatimids were also fighting with the Seljuks, so they didn't defend Jerusalem very well. The Crusaders managed to take Jerusalem, as well as some other important cities along the Mediterranean coast. They settled down there as the kings of Jerusalem, in their own new country. Many Europeans travelled back and forth, learning about math and medicine from Islamic scholars, and bringing back new foods like sugar to Europe. So the First Crusade was a big success for the Europeans, and a setback for the Fatimids.