The Prussian Crusade was a series of 13th-century campaigns of Roman Catholic crusaders, primarily led by the Teutonic Knights, to Christianize under duress the pagan Old Prussians. Invited after earlier unsuccessful expeditions against the Prussians by Christian Polish princes, the Teutonic Knights began campaigning against the Prussians, Lithuanians and Samogitians in 1230. By the end of the century, having quelled several Prussian uprisings, the Knights had established control over Prussia and administered the conquered Prussians through their monastic state, eventually erasing the Prussian language, culture and pre-Christian religion by a combination of physical and ideological force. Some Prussians took refuge in neighboring Lithuania.
Early missions and conflicts
Wulfstan of Hedeby, an agent of Alfred of Wessex, recorded the seafaring and cattle-herding Prussians as a strong and independent nation. Mieszko I of the Polans tried to extend his realm from land he had just conquered around the mouth of the Oder as far as Prussia. Bolesław I of Poland, son of Mieszko I, greatly expanded his land conquests and used Adalbert of Prague for his aim of conquering the Prussians in 997, but the missionary was killed by the natives. After some initial success among the Prussians, Adalbert's successor, Bruno of Querfurt, was also killed in 1009. Bolesław I continued
his conquests of surrounding lands and in 1015 he devastated the native populations of large parts of Prussia.
The Poles waged war with the neighboring Prussians, Sudovians, and Wends over the following two centuries. While the Poles sought control over the Prussians under the aegis of facilitating the conversion of the Prussians to Christianity, the Prussians engaged in reciprocal raids, capturing slaves in the bordering territories of Chełmno Land and Masovia. Many Prussians are alleged to have accepted baptism under duress only to revert to native religious beliefs after hostilities ended. Henry of Sandomierz was killed fighting the Prussians in 1166. Bolesław IV and Casimir II each led large armies into Prussia; while Bolesław's forces were defeated in guerilla warfare, Casimir imposed peace until his death in 1194. King Valdemar II of Denmark supported Danish expeditions against Samland until his capture by Henry I, Count of Schwerin, in 1223.
In 1206, the Cistercian bishop Christian of Oliva, with the support of the King of Denmark and Polish dukes, found colonization of the natives in a better state than expected upon his arrival in the war-torn Chełmno Land. Inspired, he travelled to Rome to prepare for a larger mission. When he returned to Chełmno in 1215, however, Christian found the Prussians hostile out of outrage at the actions of the Sword-Brothers in Livonia or fear of Christian Polish expansion. The Prussians invaded Chełmno Land, and Pomerelia, besieged Chełmno and Lubawa, and enabled Christian converts to return to their native, pre-Christian beliefs.
Because of the growing intensity of reciprocal attacks, Pope Honorius III sent a papal bull to Christian in March 1217 allowing him to begin preaching a crusade against the resisting Prussians. The following year the Prussians counter-attacked Chełmno Land and Masovia again, plundering 300 cathedrals and churches in revenge. Duke Conrad of Masovia succeeded in making the Prussians leave by paying a huge tribute, which only encouraged the Prussians, however.
Crusade of 1222/23
Honorius III called for a crusade under the leadership of Christian of Oliva and chose as papal legate the Archbishop of Gniezno, Wincenty I Niałek. German and Polish crusaders began gathering in Masovia in 1219, but serious planning only began in 1222 upon the arrival of nobles such as Duke Henry of Silesia, Archbishop Laurentius of Breslau (Wroclaw), and Laurentius of Lebus. Numerous Polish nobles began endowing Christian's Bishopric of Prussia with estates and castles in Chełmno Land during the meantime. The lords agreed that the primary focus was to rebuild the colonizing fortresses of Chełmno Land, especially Chełmno itself, whose fortress was almost completely rebuilt. By 1223, however, most of the crusaders had left the region, and the Prussians devastated Chełmno Land and Masovia yet again, forcing Duke Conrad to seek refuge in the castle of Płock. The Sarmatians (as they were then known) even reached Gdańsk (Danzig) in Pomerelia.
In 1225 or 1228, fourteen north German knights were recruited by Conrad and Christian to form a military order. First granted the estate of Cedlitz in Kuyavia until the completion of a castle at Dobrzyń, the group became known as the Order of Dobrzyń (or Dobrin). The Knights of Dobrzyń initially had success driving the Prussians from Chełmno Land, but a Prussian counterattack against them and Conrad killed most of the Order. The survivors were granted asylum in Pomerania by Duke Swantopelk II. The Order of Calatrava, granted a base near Gdańsk, was also ineffective.
Invitation of the Teutonic Order
While in Rome, Christian of Oliva had made the acquaintance of Hermann von Salza, the Grand Master of the Teutonic Order from 1209 to 1239. With the permission of Duke Conrad of Masovia and the Masovian nobility, Christian requested aid from the Teutonic Order against the Prussians in 1226. Stability with the Prussians would then allow Conrad to pursue becoming High Duke of Poland. While Hermann was interested in the Polish offer, his focus was on assisting Emperor Frederick II with the Fifth Crusade. Because the Teutonic Order had recently been expelled from the Burzenland in the Kingdom of Hungary, Hermann also desired greater autonomy for his forces in future endeavors.
Hermann met with Frederick II at Rimini and suggested that the subjugation of the Prussians would make the Holy Roman Empire's borders easier to defend against invaders, presumably referring to Lithuanian counterattacks against Christian crusades. The Holy Roman Emperor gave his approval of the enterprise in the Golden Bull of Rimini of 1226, granting them Chełmno Land, or Culmerland, and any future conquests. The mission to convert the Prussians remained under the command of Bishop Christian of Oliva.
Before beginning the campaign against the Prussians, the Teutonic Order allegedly signed the Treaty of Kruszwica with the Poles on 16 June 1230, by which the Order was to receive Culmerland and any future conquests, similar to the terms of the Golden Bull of Rimini. The agreement has been disputed by historians; the document has been lost and many Polish historians have doubted its authenticity and the Teutonic Order's territorial claims. However, recent studies by Polish historians have established the treaty's legitimacy. From the viewpoint of Duke Conrad, Chełmno was only to be used as a temporary base against the Prussians and future conquests were to be under the authority of the Duke of Masovia. However, Hermann von Salza saw the document as granting the Order autonomy in all territorial acquisitions, aside from allegiance to the Holy See and the Holy Roman Emperor. The Golden Bull of Rieti issued by Pope Gregory IX in 1234 reaffirmed the Order's control of conquered lands, placing them only under the authority of the Holy See.
The 14th century chronicler Peter von Dusburg mentioned eleven districts in Prussia: Bartia, Culmerland (formerly under Polish control), Galindia, Nadrovia, Natangia, Pogesania, Pomesania, Samland, Scalovia, Sudovia, and Ermland. Peter estimated that while most tribes could muster about 2,000 cavalry, Samland could raise 4,000 cavalry and 40,000 infantry, while Sudovia had 6,000 cavalry and "an almost innumerable multitude of other warriors". In contrast, the Prussians of ravaged Culmerland could raise fewer troops than the other tribes. Galindia, a forested wilderness of lakes and rivers, also had a small population to raise troops from. Modern estimates indicate a total Prussian population of 170,000, smaller than that suggested by Peter von Dusburg.
Initial Teutonic campaigns
After receiving or forging the claim to Culmerland in 1230, Hermann von Salza dispatched Conrad von Landsberg as his envoy with a small force of seven Teutonic Knights and 70–100 squires and sergeants to Masovia as a vanguard. They took possession of Vogelsang (German for "bird song"), a castle being built by Conrad opposite the future Thorn (Toruń). Other sources indicate that two knights constructed Vogelsang in 1229, but were killed by Prussians soon after. Soon after arriving at Vogelsang, Conrad von Landsberg began ordering small raids against pagans on the south side of the Vistula, a region that was relatively safe with a mixed Christian and pagan population. Reinforcements began arriving at Vogelsang after the castle's completion. Led by Hermann Balk, a force numbering twenty knights and 200 sergeants arrived in 1230.
While the earlier Polish expeditions had usually marched eastward into the Prussian wilderness, the Order focused in the west to establish fortresses along the Vistula River. They campaigned annually whenever crusading knights from the west arrived. The early campaigns were primarily composed of Polish, German, and Pomeranian crusaders, as well as some Prussian militiamen auxiliaries. The Polish and Pomerelian dukes proved essential through their providing of troops and bases. Most of the secular crusaders would return to their homes after the end of the campaigns, leaving the monastic Teutonic Knights the task of consolidating the gains and garrisoning the newly built forts, most of which were small and made of timber. Some secular Polish knights were granted vacant territories, especially in Culmerland, although most of the conquered territory was retained by the Teutonic Order. Colonists from the Holy Roman Empire began to immigrate eastward, allowing the foundation of a new town each year, many of which were granted Kulm law.
The crusaders began campaigning against the neighboring Pomesanians and their leader Pepin. Advancing from Nessau (Nieszawa) with the aid of Conrad of Masovia, Balk took control of ruins at modern Toruń and advanced toward the pagan-occupied Rogów. A local Prussian captain defected and handed that castle to the crusaders, who then destroyed the Prussian fort of Quercz or Gurske. The defecting captain then tricked Pepin into being captured by the Knights, ending Prussian resistance in the Culmerland. By 1232, the Knights had established or rebuilt fortresses at Culm (Chełmno) and Thorn. Pope Gregory IX called for reinforcements, which included 5,000 veterans under the leadership of the Burgrave of Magdeburg.
In summer 1233, the Knights led a crusading army of 10,000 and established a fortress at Marienwerder (Kwidzyn) in Pomesania. The Pomerelian dukes Swantopelk and Sambor supported a smaller army for an invasion of Pogesania during the winter of 1233–34. After a close battle, the pagan Pogesanians were routed on the frozen Sirgune River by the arrival of the ducal cavalry, and the battlefield was subsequently known as the "Field of the Dead". The building of a fortress at Rehden (Radzyń Chełmiński) stabilized the eastern Culmerland in 1234.
The bishop of Prussia, Christian of Oliva, claimed two-thirds of conquered territory, granting one-third to the Teutonic Order. The papal legate William of Modena mediated between the two sides, granting the Knights two-thirds but reserving extra rights for the bishop. The Teutonic Knights also sought the incorporation of the small Order of Dobrzyń into the larger Teutonic Order. Conrad of Masovia was furious with this proposal and demanded the return of the Dobrzyń Land, which the Knights were reluctant to do; Duke Conrad subsequently refused to aid the crusaders any further. With the approval of the pope and the bishop of Płock, the Teutonic Knights assimilated the Order of Dobrzyń in a bull on 19 April 1235; the displeased Conrad of Masovia had the castle of Dobrzyń returned to him. In 1237 the Teutonic Knights assimilated the Sword-Brothers or Livonian Order, a military order active in Livonia, after they were nearly wiped out by Lithuanians in the Battle of Saule.
With the support of Henry III, Margrave of Meissen, in 1236, the crusaders advanced north along both banks of the Vistula and forced the submission of most Pomesanians. Although Henry did not participate in the 1237 campaign against the Pogesanians, the margrave supplied the Order with two large river-boats which defeated the smaller craft used by the Prussian tribes. Near the Prussian settlement of Truso, Elbing (Elbląg) was founded with colonists from Lübeck, while Christburg (Dzierzgoń) protected the land east of Marienwerder.