Pope Urban II calls the first crusade - this event was caused as Byzantine Emperor Alexius I made an appeal to Urban for assistance. Urban united Christian Europe to fight against the Turks to take back the Holy Land.
Urban degraded Muslims in speeches with exaggerating stories of anti-Christian acts, giving the united Christian Europe a common enemy and a promised reward.
The Christians were, however, initially beaten back due to inexperience and lack of discipline.
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A possible reason was the attacks on them by crusaders and mongols around the 11th and 12th centuries. Another reason could have been the Arab rulers removing taxes from non Muslims and doing other things that hurt there income.
He was a president and i think he was assassinated.
