Theword"crusade"nowusuallyhaspositiveovertoneswhich,however,bearnorelationtohistoricalevents.TheFirstCrusade,forinstance,resultedinthecaptureofJerusaleminJuly1099andthemassacreofaround40,000unarmedciviliansinthecity.
Atthetime,theCrusadersviewedthisactofgenocideasagloriousvictory.ThefollowingaccountbyRaymondd'Aguiliers,aneyewitnessoftheFirstCrusadeandoneofitsmostimportantchroniclers,isveryrevealing:"Nowthatourmenhadpossessionofthewallsandtowers,wonderfulsightsweretobeseen.Someofourmencutofftheheadsoftheirenemies;othersshotthemwitharrows;otherstorturedthemlongerbycastingthemintotheflames.Pilesofheads,handsandfeetweretobeseeninthestreets....ItwasajustandsplendidjudgmentofGodthatthisplaceshouldbefilledwithunbelivers'blood."
英文crusade（像十字軍般致力除惡）一字，今天一般有褒義，但這不符合史實。例如第一次十字軍興師，一○九九年七月攻陷耶路撒冷，屠殺了城中約四萬個手無寸鐵的平民。
當時，十字軍視這場種族屠殺為光榮勝利。雷蒙．德阿吉萊爾斯目覩第一次十字軍戰事，所撰戰史是這場戰爭的重要記錄之一。他以下一段描述說得很明白：「我軍攻佔城牆城堡之後，美妙的事就發生了。敵人或被斬首，或被箭射死，或被拋進火焰之中，教他們多挨一會才死亡。街上堆滿人頭和手腳……上帝公平的判決，赫赫明明，就是要這裏不信基督之輩血流成河。」