It is human nature to war and fight. If someone believes that something is their property, then they will fight for it. The Crusades, a series of brutal battles and sieges, were started by the Christians from 1095-1291. Although manors were separate, the main unifying factor was the Roman Catholic Church, it had all the power.
There were multiple causes for the Crusades; however the two most important causes were the differences between the Muslim and Christian religions, and the stories of the atrocities done to the Christians. Jerusalem was the holy land for the Muslims because it housed the Dome of the Rock. Jerusalem was the holy land for the Christians because it was the place where Jesus, the founder of Christianity, lived and preached. The second cause of the Crusades was the stories of the horrible slaughters and genocides that the Muslims did to the Christians that were living in their territory.
There were four main Crusades; however, there were about five other smaller ones. Overall they were relatively unsuccessful. The First Crusade started when Byzantine Emperor Alexius I asked for about three-hundred well trained soldiers from the western Christians for protection against the Seljuk Turks. He received about 10,000 poorly trained peasants, which was not what he wanted. So, they were sent to the Muslim City of Nicaea and captured that, next they marched towards Antioch; it was finally captured after a long grueling siege. As for the 2nd, 3rd, and 4thCrusades, each one was unsuccessful at taking Jerusalem.
Although the Crusades were not directly successful, they did prove to produce long lasting improvements. Mainly, the Crusades opened the door for trading with the East. Along with trading came new navigational skills and tools, like the magnetic compass, to the Christians. Because of more advanced ships and navigation, Westerners could travel farther, thus leading to an explosion of exploration. New ideas in Mathematics, Science, Literature, Astronomy, and Architecture were introduced to the Christians. Exotic foods and spices from the East became luxuries in Eastern European households.
Warring and crusading leads to expansion, trade, and knowledge. The Crusades would lead to what is known as the Renaissance, or re-birth of Christian society. Although the battle was lost, the war can still be won.