Golden Bull of Rimini
The Golden Bull of Rimini was a Golden Bull issued by Emperor Frederick II, at his court in Rimini in March 1226 to confirm the Teutonic Knights' possessions in Prussia. It was the first of three similar documents, followed by the Treaty of Kruszwica (Kruschwitz) in 1230, and the papal Golden Bull of Rieti in 1234.
The Piast duke Konrad I of Masovia had waged several Prussian Crusades and particularly in 1222/23 had tried to conquer Chełmno Land (Culmer Land) east of the Vistula River from the pagan Old Prussians. Backed by his Polish cousins Leszek I the White and Henry I the Bearded, he initially was successful, but had to face a Prussian counterstrike and now feared for his Duchy of Masovia, which suffered under continuous Prussian attacks. In 1224 the duke began negotiations with the Teutonic Knights to strengthen his forces and to stabilize the situation.
Between 1211 and 1225, the Teutonic Order, led by Grand Master Hermann von Salza, was present in the Burzenland region of Transylvania. Similar to Konrad of Masovia's request, the Knights had been called in by King Andrew II of Hungary to settle, stabilize and protect the eastern Hungarian frontier against the Cuman people. Yet, they were expelled after trying to establish an autonomous state on Hungarian territory, subordinate only to the authority of Pope Honorius III. This time von Salza would wait to set out for Prussia, until the Order's claimed possessions were confirmed directly by the Holy Roman Emperor.
The Bull 
The Knights were to be equipped by Duke Konrad I of Masovia in exchange for their support to stabilize his Masovian land:
Brother Konrad had offered and promised to furnish brother Hermann, Honorable Master of the Holy Hospital of St. Mary /of the Germans in Jerusalem (Teutonic Order)...with the land of Culm (Chelmno) between his march and the Prussians and equip them (T.O.) well, so they may take Prussia in possession... we recognize the fact, that this land is included in the realm of the empire, we trust the judgement of the Master... we recognize all land in Prussia as an ancient right of the empire ...
This Imperial authorisation was signed by a large number of princes, like the Archbishops of Magdeburg, Ravenna, Tyre, Palermo and Reggio, the Bishops of Bologna, Rimini, Cesena, Mantua and Tortosa, the Dukes of Saxony and Spoleto, and the Margrave of Montferrat.
Later confirmation 
Duke Konrad actually had no intention to cede Chełmno Land and therefore established his own military Order of Dobrzyń (Fratribus Militiae Christi) in 1228, whom he vested with Dobrzyń Land. The few brothers however were not able to secure the Masovian borders against the Prussian raids and Konrad faced the threat of losing his whole duchy.
Treaty of Kruszwica 
On 16 June 1230, the Treaty of Kruszwica was supposedly signed, according to which Duke Konrad ceded the Teutonic Knights under Grand Master Hermann von Salza and the Order of Dobrzyń the lands of Chełmno as well as all other conquests made in Prussia. The text is only known by later references, as the original document is not preserved. According to the historian Max Perlbach (1848-1921), the Knights had forged it to create a legal basis for their secular possessions.
Golden Bull of Rieti 
In 1234, Pope Gregory IX issued the Golden Bull of Rieti Pietati proximum, confirming the prior deals, stating that the Prussian lands of the Order were only subject to the Pope, not a fief of any other secular or ecclesiastical power. The Roman Curia had already made a conform promise, nevertheless von Salza had insisted to set it down in writing
The bull was again confirmed by Pope Alexander IV in 1257.
See also 
- According to historian Tomasz Jasiński, Kruschwitz, Rimini und die Grundlagen des preußischen Ordenslandes. Urkundenstudien zur Frühzeit des Deutschen Ordens im Ostseeraum, the bull was backdated and actually issued in 1235.