The expulsion of the Jesuits from Spain and her possessions represents a historical question mark, in so far as the decisive factors which led to that event are still far from being clear. Ludwig von Pastor's dictum that the whole affair was a most secretive one remains the one conclusion beyond doubt. Historians have presented various hypotheses on the causes for expulsion, but none of them are conclusive or definitive. Among the more probable and plausible of these hypotheses, that of the regalist policies of the Spanish Crown appears to be the most convincing. In effect, regalism as an antithetical force to the organization and activities of the order has been implied by nineteenth and twentieth-century Spanish historians, although they tended to view the “Cloaks and Hats” riot of 1766 as the essential cause of the Jesuits' expulsion.