What did Pope Urban II promise the crusaders?

By 1095 CE, conflict erupted in what is today called the Middle East. Similar to today, different religious groups claimed Jerusalem as their Holy Land. Seljuk Turks, who were Muslims, controlled Jerusalem and barred Christians from the city, preventing them from making holy pilgrimages. The Turks were also threatening to take control of Constantinople (present-day Istanbul), which at the time was controlled by the Christian Byzantine Empire. The Byzantine Emperor Alexius I asked Pope Urban II for help in defending Constantinople and retaking the Holy Land from the Turks.
Pope Urban II called the Council of Clermont in France, urging Christians to unite against the Turks, whom he portrayed as barbarians. He promised complete forgiveness of sin for all those who took part in the crusade. This promise was significant because, in the Catholic Church, sins could only be forgiven through confession to a priest.