The First Crusade
Bishop Adhemar
The papal legate for the First Crusade was Adhemar, Bishop of Le Puy. Adhemar was a bishop of the old school, well able to ride a horse and to wear armor. Adhemar would demonstrate his military ability more than once on the crusade.
A papal legate was someone chosen by the pope to act on his behalf in a certain matter. A legate might be sent to negotiate a treaty, to settle a dispute, even to crown a king if the pope himself could not go. In choosing a legate to accompany the crusade, Pope Urban was clearly signalling that the papacy should be represented in all that the crusade might accomplish.
More than this we do not know. Did Urban intend that the crusade should be led by the Church rather than by the laity? Did he mean that Adhemar should become the Patriarch of Jerusalem? The sources don't say, and Adhemar died at Antioch, so we cannot tell from his actions, either. All armies were accompanied by priests; perhaps since the pope had called this army into existence, he merely was providing a chief priest for the expedition.
We cannot know the answer to this question, but the larger question will recur throughout the twelfth century: who should lead a crusade? Was a crusade only called into existence by a pope? Should it be directed only toward those ends he set? What if the crusaders diverged from those ends? We will return to this question. In the case of the First Crusade, the lay lords took command early and kept it throughout.