The Crusades, 1095 – 1291. In March 1095, Byzantine Emperor Alexios I Komnenos sent his ambassador to call for help with defending his empire against the Muslim Seljuk Turks. Pope Urban II, at the Council of Clermont held in November of the same year, summoned the attending nobility and the people to wrestle the Holy Land from the hands of the Seljuk Turks. Crusader armies marched on Jerusalem, sacking several cities on their way. In 1099 they took Jerusalem and massacred the population.