Hello! Last semester for my Historical Analysis research paper, I presented a thesis that there is a common misconception that the First Crusade was solely based on liberating Jerusalem from Muslim rule, but underlying that was Pope Urban II using the events that happened at Jerusalem as a scapegoat to appeal to a massive Christian population in order to expand Western Roman rule in hopes to reunite both the Western and Eastern empires under his rule at the head of the papacy. I fervently believe that my first 6 pages giving historical background in regards to Pope Leo IV and Pope John VIII using the same promise of eternal life for those who fought and died against the "pagans" and the remission of sins, as well as Saint Augustine's assurance that the commandment forbidding killing is not broke by those who wage war on the authority of God was rightfully there, but when it came down to it, I couldn't find enough primary material backing my claim due to poor time management (other papers included Roman Homosexuality primarily based on dominance, Chinese women's role and status in Song China, and the effects of being a minority culture living in a dominant culture).
There is no evidence of an ulterior or master plan to distract or trick the masses with an armed pilgrimage in. Urban's motivations can be a bit difficult to parse out, but there is no strong reason to doubt he sincerely believed the Holy Sepulchre and Christians in the East were in danger and that the direction of lay violence towards more 'appropriate' outlets would ultimately be to the benefit of Christendom. The First Crusade did help solidify Urban's position in the Latin West and presented the opportunity to mend relations with Constantinople and advance papal prestige in the East, but I would caution against a reading that views these advantages as hidden political motives to be kept concealed or as contradictory to the goal to free Christians and Christian sites. The desire to liberate Jerusalem is entirely consistent with the reform movement's goal of a more united Christian community.
The dream of a single Christendom and papal preeminence were part and parcel of the reform movements and are rooted in the theological and religious climate of the eleventh century. It would be unwise to separate the religious from the political in the medieval period. Such divisions often lead to conclusions that individuals used religion to accomplish their real goals. Not that people in the past could not be just as dishonest and duplicitous as us, but such arguments usually rest on misunderstandings about the pervasiveness of the religious in medieval life.
Could you perhaps clarify what you mean when you mention that Urban II had a plan to unite the West with the East? The extent to which your are claiming a concrete plan existed would be necessary to evaluate your claims.