The crusades were a response to Muslim aggression where over 2/3 of Christian land was conquered by Muslim forces, some of the most cruel and barbaric people the world has ever seen. The Crusades stopped Muslim expansion and pushed them back, never to really recover. Muslims and Jews are still traumatized by the Crusades.
https://www.youtube.com/watch?v=RuxqXjhl13YIslam gave the world nothing but death and destruction. Every magnificent civilization they conquered, they turned into a third world Islamic hell hole, never to recover. From the great Egyptian (Coptic) Empire, Persian Empire, to the Byzantine Empire. One thousand years after the Christian Cathedral Hagia Sophia was built, the Muslim Ottoman Turks wanted to build something better and grander. After many years they had to give up and built the Blue Mosque, a smaller and more ugly version of Hagia Sophia. That is as if the Muslims conquered Europe today, they still even in the year 3 000 would have problems building the bridges, airports, and technical installations we have today.
Islam always imposed a very harsh arabification of their conquered peoples. You have to pray in Arabic, read the Qur'an in Arabic, dress like an Arab desert dweller etc. The native language of the Egyptian people (Copts) that built the world-renowned pyramids is now dead, after Muslims cut the tongue of every Copt that spoke Coptic around the Muslim Arabs, who were afraid that the Copts would curse them. Turks imposed the same rule, but were afraid that the Byzantines would curse them silently, so Turks have amulets of blue eyes, especially on children (still sold in Turkey today), to protect them against "the evil eye" from the Byzantines that had their women raped and wealth plundered.
Without the crusades, there would have been no white Europe or North America. We would all have been brown rape-babies, with double-digit IQ and speaking Arabic in a third-world Islamic hell hole.
Only a new crusade can save us