名次解释,什么是 "十字军东征(crusades)"

是要英文解释吗？下面这些网站有1
http://www.newadvent.org/cathen/04543c.htm
http://www.kyrene.org/schools/brisas/sunda/ma/1kyle.htm
http://crusades.boisestate.edu/

Proud knights in the Crusades would march towards forgiveness of their sins, filled with greed. Bloodshed, they believed, was worth it, dying was worth it. Marching towards Jerusalem with victory in their eyes, they would take anyone who stood in their way of victory. That was the Crusades of the Middle Ages.

In the year 1095, people were shocked in Western Europe by the words of Pope Urban II, "The Muslims have conquered Jerusalem". Pope Urban wanted the Christians to retake Jerusalem from the Muslims.