The Crusades were a late, small-scale, defensive action after 450 years of Islamic jihad had conquered and Islamized over half of the Christian world. “But the myth that the Crusades were unprovoked protocolonial aggression against a wholly innocent Muslim world persists, and has even made its way into public school textbooks, which have long been the object of efforts by Islamic supremacist groups to turn them into vehicles for proselytizing for Islam.”

From Islam 101.

Islam conquered all those bright red and green areas — which were mainly Christian and Jewish before conquest. Christians managed to reconquer the bright red areas. The reconquest in the middle east are the result of the crusades, which halted the Muslim conquest of Europe by temporarily holding that territory and diverting the Muslims.

hat-tip Stephen Neil