Pope Eugenius III, who had been a monk at Clairvaux under Bernard, commissioned him to preach the Second Crusade after the fall of Edessa. He preached it at Vezelay at Easter 1146 before the king of France, and the response was large enough that he reported having to tear his own habit into strips because the supply of cloth crosses ran out. He then wrote and travelled through France and the Rhineland raising the German king as well.
In the Rhineland he did something that is not usually associated with crusade preaching. A monk named Radulf was preaching that the campaign should begin by killing Jews at home, and massacres had followed. Bernard went to the region, confronted him publicly, and sent letters insisting that Jews were not to be touched, arguing that they were living witnesses and that violence against them was forbidden. Contemporary Jewish chroniclers record his intervention and credit it with saving lives.
The expedition failed completely, and its failure was laid at his door by people who had gone because he told them to. He did not deflect it. In his treatise On Consideration, written for Eugenius, he faced the charge directly, accepted his share and argued that the fault lay in the sins of the crusaders rather than in the call.
The episode is the clearest measure of his position: a monk with no bishopric who could raise armies with a sermon, restrain a pogrom with a letter, and then be held publicly responsible when the armies were destroyed.