The crusades were ultimately won in the East by the Muslims when the Bahri Mamluks conquered Acre in 1291. While crusades were mounted even after this point, political witch-hunts mounted against the Knights Templar by King Philip IV of France made further major crusades in the Levant impractical.
The crusades began when, after over 200 years of Muslim attacks on Western states including Rome itself, the Byzantine Emperor Alexius Comnenus requested help in reclaiming land in Asia Minor that had been taken by the Seljuk Turks. In 1096, Pope Urban II declared an armed pilgrimage to take back Jerusalem. While this crusade succeeded, the lands in question were passed back and forth for two centuries until the Christians were defeated.
In Spain, the 700-year-long Reconquista pushed out the Muslim Moors and reinstated Christianity in 1491. This conflict shared many of the same traits as the Holy Land crusades.