Actually, it was more often referred to as a peregrinatio ad hierusalem - a pilgrimage to Jerusalem. This is by far the most common term for crusade in crusade narratives. The main account we have from the failed Second Crusade, for example, is Odo of Deuil's De profectione Ludovici VII in Orientem - "Concerning the Journey of Louis VII into the East" - which gives the same message.

Modern popular history tends to portray the crusades as an ARMED pilgrimage, while this phrase reminds us that it was in the minds of contemporaries an armed PILGRIMAGE.