What were the negative impacts that the crusades had upon the Christians?

-Due to crusades mutual hatred between religions like Islam (for obvious reasons) and Orthodox church (sacking Costantinople in 1204) has grown.

-Since kings were occupied by crusades and neglected what was going on in their own country (like Richard the Lionheart).

-Many people died due to hardships of travels, fighting, starvation due to pillage.

-Rulers, died and this caused turmoil in their countries.

Jerusalem fell under the control of the Seljuk Turks, who were also Muslim. However, the Seljuk Turks were less willing to let Christian pilgrims visit Jerusalem. They swept in from the east and attacked Christians, killing some and selling others as slaves. That's why the Pope urban II called the people for fighting against the Turks.