The Golden Bull of Rimini was a decree issued by Emperor Frederick II in Rimini in March 1226 that granted and confirmed the privilege of territorial conquest and acquisition for the Teutonic Order in Prussia. According to historian Tomasz Jasiński, the bull was backdated and had actually been issued in 1235. It represents the first of a series of three documents, that include the Treaty of Kruschwitz of 1230 and the Papal Golden Bull of Rieti of 1234. Background The Piast duke Konrad I of Masovia had since 1209 engaged in several military campaigns against the pagan Old Prussians. In 1217 Pope Honorius III authorized bishop Christian of Oliva to designate these conquests as the Prussian Crusade. In 1222/23 Konrad attempted to subdue the Prussian territories of the Culmer Land east of the Vistula River. Backed by his Polish cousins Leszek I the White and Henry I the Bearded, he initially was successful, but was eventually confronted with relentless Prussian counter attacks and incursions across the borders into his Masovian lands. The military Order of Dobrzyń, founded by bishop Christian in 1225 (or 1228) lacked strength and numbers to successfully contain the Prussians and was soon destroyed. Prussian forces at last threatened the integrity of Konrad's Duchy, attacking his residence at Płock Castle. Konrad took up negotiations with the Teutonic Order in 1226 to have them join his forces and stabilize the situation. The Teutonic Order, under the command of Grand Master Herman of Salza, had been on campaign in the Burzenland region of Transylvania since 1211. The Knights of the order had been called in by King Andrew II of Hungary to settle and stabilize the eastern Hungarian frontier and protect it against the Cumans. In 1225 King Andrew expelled the order after they had attempted to establish an autonomous monastic principality on Hungarian territory, subordinate only to the authority of Pope Honorius III. Now, von Salza would wait to only set out for Prussia, after the Order's claimed possessions were confirmed directly by the Holy Roman Emperor. The Bull The Knights were to be supported by Duke Konrad I of Masovia in exchange for their conquest and subjugation of the heathen Prussian tribes: ...our trusty Brother Herman, the worthy Master of the Sacred House of the Hospital of St. Mary of the Germans in Jerusalem [i.e., the Teutonic Order] has explained ... that our devoted Konrad (Chünradus), Duke