The Crusades spread Christianity, expanded the territories of many European countries, increased trade, spread knowledge and began an era of persecution and war against non-Christians that continued with the Inquisition. The Crusades also dramatically increased the wealth and power of the Roman Catholic Church.
The First Crusade was in 1095, when Pope Urban II called for an expedition to take Jerusalem from the Turks, who had harassed Christian pilgrims. There were regular crusades against the Middle East and parts of Africa until almost 1300. Crusaders rediscovered many ancient Greek and Roman texts by exploring Middle Eastern libraries. Many merchants became rich by transporting crusaders in their ships and trading with Muslims. The potential wealth motivated later explorers like Columbus to find new lands for conquering and trading.