You might be interested in this earlier answer of mine:
A taste to begin with:
Any story of Jews and Crusaders has to start with the failed "zero Crusade," the first mass armed attempt to reach the Holy Land. The crusader army got more than a little side-tracked and ended up rampaging across the cities of Germany, massacring Jewish populations. Shlomo Eidelberg has translated and published the Jewish martyr chronicles of these first western pogroms (The Jews and the Crusades: Hebrew Chronicles of the First and Second Crusades). It is heartwrenching to read about how news of the earliest mass murders reached Jews in nearby cities, so they knew what was coming, and also that there was no escape. You read about the local bishop trying to offer protection, about Jewish men donning their armor, about mothers throwing down rocks into the courtyard as knights in shining armor slaughter their husbands, only to be forced to kill their own children ("sanctifying the name of the Lord") before the knights can seize them for baptism into Christianity.
The Crusaders who reached the Near East, of course, were not exactly famous for discriminating among the local population...