Old Prussians
Konrad of Masovia had already called a crusade against the Old Prussians in 1208, but it was not successful. Konrad, acting on the advice of Christian, first bishop of Prussia, established the Order of Dobrzyń, a small group of 15 knights. The Order, however, was soon defeated and, in reaction, Konrad called on the Pope for yet another crusade and for help from the Teutonic Knights. As a result, several edicts called for crusades against the Old Prussians. The crusades, involving many of Europe's knights, lasted for sixty years.