What brought about the crusades initially and why were continued in the third and fourth crusades? (be sure to consider the roles of emperors of the byzantine empire, pope urban ii, and later religious fervor in the cities.) ?

The christians wanted to have "adventure and new life and wealth" so they attacked the muslims and one the first crusade. The next three crusades were the muslims win because this time they were prepared. Muslims were much more sophisticated than the christians