A crusade that formed part of the conflict over episcopal prerogatives and doctrinal observance between the bishopric of Utrecht and the inhabitants of the Drenthe region in the northeastern Netherlands.
After the murder of Bishop Otto II of Utrecht by the Dren- thers in 1227, his successor Willibrand of Oldenburg turned the conflict into a crusade for the defense of episcopal rights and authority in Drenthe. Even though no papal bull has survived, the Gesta episcoporum Traiectensium clearly states that Willibrand was acting with papal authority; he may have obtained the relevant powers directly from Pope Gregory IX. The justification of the crusade was presumably that the Drenthers had defied their bishop’s authority, which technically made them heretics. Willibrand was reported to have preached the cross in Frisia several times between the late summer of 1228 and winter of 1230-1231. After a number of encounters between the bishop’s forces and the Drenthers, the crusade came to an end in September 1232.