Theme:both sides of an issue
Thesis:Everything has its benefit and its drawback
Detail: The Crusades, profoundly altering European history, were a series of attacks organized by Western Christians in order to take control of the holy city of Jerusalem from Muslim powers. Although they generally failed in their chief purpose, the Crusades exercised an immense influence on Western civilization by bringing the West into closer contact with new ways of living and thinking--stimulating commerce, giving fresh impetus to literature and invention, and increasing geographical knowledge.
Example also serves:It is really impossible to fail.