Final answer:
Byzantine Emperor Alexius sought practical military support to secure his empire, while Pope Urban II envisioned the First Crusade as an armed pilgrimage that served the Catholic Church's spiritual, reformist, and political agendas.
Step-by-step explanation:
The First Crusade was initiated under vastly different intentions by Byzantine Emperor Alexius I and Pope Urban II, each hoping to benefit in particular ways from the expedition. Emperor Alexius sought military aid to defend his empire against Seljuk encroachment and possibly restore lost territories, essentially looking for mercenaries to bolster Byzantine forces. His request to the pope was practical and politically motivated, focusing on the strength and security of his own realm.
On the other hand, Pope Urban II saw an opportunity to advance the interests of the Catholic Church. By proclaiming the crusade as an 'armed pilgrimage' to liberate the Holy Land, Urban II linked the endeavor to the religious fervor of the time and positioned it within the church's broader reformist agenda. Moreover, the pope aimed to heal the schism between the Eastern and Western Christian churches while simultaneously curbing the violent tendencies of the European aristocracy by redirecting their martial energies toward what he presented as a noble cause—the defense of Christians and the reclaiming of Jerusalem.
Ultimately, the crusaders established a Latin Christian state known as Outremer in the Middle East, which was a source of disappointment for Emperor Alexius, who had expected the return of lands. Pope Urban II's vision, however, extended beyond immediate military goals to encompass spiritual and ecclesiastical benefits, such as uniting Christendom and strengthening the papacy's authority over secular rulers like the German emperor who challenged his power.