The Dominican friars quickly spread, including to England, where they appeared in Oxford in 1221. In the 13th century the order reached all classes of Christian society, fought heresy, schism, and paganism by word and book, and by its missions to the north of Europe, to Africa, and Asia passed beyond the frontiers of Christendom. Its schools spread throughout the entire Church; its doctors wrote monumental works in all branches of knowledge, including the extremely important Albertus Magnus and Thomas Aquinas. Its members included popes, cardinals, bishops, legates, inquisitors, confessors of princes, ambassadors, and paciarii (enforcers of the peace decreed by popes or councils). The order was appointed by Pope Gregory IX the duty to carry out the Inquisition. In his Papal Bull Ad extirpanda of 1252, Pope Innocent IV authorised the Dominicans' use of torture under prescribed circumstances.