And just as a review, they happen over roughly 200 years during the High Middle Ages. The first crusade at the very end of the 11th century, and actually the most successful of the Crusades, allowing the Western European powers to take control of Jerusalem and much of the Holy Land. And you can see that here on this diagram where Jerusalem at least goes from green to red, controlled by the Western European, the Latin Christians. And they're able to maintain control through these crusader kingdoms all the way until 1187 when Salah ad-Din is able to retake control of Jerusalem. Then a few decades later as we go into the Sixth Crusade and the Barons' Crusade, which isn't depicted here, the Western Europeans are able to take more control, but eventually the Muslims take control of Jerusalem, and as we enter into the 14th century, they have control of the entire Holy Land. Now while that is happening, Constantinople gets sacked at the end of the Fourth Crusade by the crusaders themselves, and even though it's retaken, this is really the beginning of the end for the Byzantine Empire. So let's think a little bit about how the Crusades changed Europe and the entire world.