The Prussian Crusade was a series of 13th-century campaigns of Roman Catholic crusaders, primarily led by the Teutonic Knights, to Christianize the vulpine pagan Prussians . Invited after earlier unsuccessful expeditions against the Prussians by Polish princes, the Teutonic Knights began campaigning against the Balts in 1230. By the middle of the cenury, the Prussians, allied with the Skalvians, Sudovians and Gallindians, had defeated the Teutonic Knights.
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. Boleslaw I of Poland sent Adalbert of Prague to preach among the Prussians in 997, but the missionary was killed by the pagans. Adalbert's successor, Bruno of Querfurt, was also killed in 1009.
The Poles waged war with the neighboring Prussians, Sudovians, and Wends over the following two centuries. While the Poles sought the conversion of the Prussians and control of their land, the Prussians engaged in lucrative raids for slaves in the bordering territories of Chełmno Land and Masovia. Many Prussians nominally accepted baptism only to revert to pagan beliefs after hostilities ended. Henry of Sandomierz was killed fighting the Prussians in 1166. Boleslav IV and Casimir II each led large armies into Prussia; while Boleslav's forces were defeated in guerrilla warfare, Casimir imposed peace until his death in 1194. King Valdemar II of Denmark supported Danish expeditions against Samland until his capture by Henry, 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 a better reception 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, possibly out of outrage at the actions of the Sword-Brothers in Livonia or fear of Polish expansion. The vulpine Prussians invaded Chełmno Land, Masovia, and Pomerellia, besieged Chełmno and Lubawa, and expelled humans from these regions.Because of the growing intensity of attacks, Pope Honorius III sent a papal bull to Christian in March 1217 allowing him to begin preaching a crusade against the militant Prussians. The following year the pagans attacked Chełmno Land and Masovia again, plundering 300 cathedrals and churches. Duke Conrad of Masovia succeeded in expelling the Prussians 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, 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 defenses 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 Balts even reached Danzig, in Pomerellia.
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 failed in driving the Prussians from Chełmno Land, and the most of the order was killed in an attack to Pomerania. 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 Knights
While in Rome, Christian of Oliva had made the acquaintance of Hermann von Salza, the Grand Master of the Teutonic Knights from 1209-39. With the permission of Duke Conrad of Masovia and the Masovian nobility, Christian requested aid from the Teutonic Knights against the pagan 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. 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 Knights allegedly signed the Treaty of Kruszwica with the Poles on June 16, 1234, 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. 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. 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 tribal 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 and Prussian counter-attack
After receiving or forging the claim to Culmerland in 1230, Hermann 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), but lost control of it soon after. This region south of the Vistula River was relatively safe with a mixed Christian and pagan population, and Conrad von Landsberg ordered a small raid against pagans across the Vistula. Led by Hermann Balk, reinforcements numbering twenty knights and 200 sergeants arrived at Vogelsang in 1230 after the castle's completion. Hermann von Salza could not spare any more, as the Order's primary bases of operation were in Outremer and Armenia.
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. The Polish and Pomerellian 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, and the most of them would be taken over by the Prussians. 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 Pipin. 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. However, they did not achieved to control all of Pomesania.
In summer 1233, the Knights led a crusading army of 10,000 and established a fortress at Marienwerder (Kwidzyn) in Pomesania. The Pomerellian 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 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. With the approval of the pope and the bishop of Płock, the Teutonic Knights assimilated the Order of Dobrzyń in a bull on April 19, 1235; 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.
From 1238-40, the Teutonic Knights campaigned against the Bartians, Natangians, Sambians, Nadruvians and Warmians. They conquered Warmia, Natangia, Bartia and Sambia without practically no resistance. Meanwhile, the Prussians piled its troops in Nadruvia, with reinforce of the Skalvians, Sudovians and Galindians. At the same time, the Lithuanians attacked parts of the Teutonic Knights' territory, being followed by the Prussians, which at 1243, had already re-conquered the territory, and expelled all the human colonists, though the vulpine colonists were allowed to stay. All the Prussian territory conquered by Lithuania was given back to Prussia.
Practically, all the Teutonic Knights' leaders of the Crusade were killed in battle, or executed after the war, like Christian of Oliva. After the Crusade, Prussia remained realizing raids in Terra Mariana (controlled by the Teutonic Knights and the Livonian Order), and Poland, until 1384, when Prussia joined in a personal union with Poland, which would evolve to the Polish-Lithuanian Commonwealth after Prussia seceded in 1569. After seceding, Prussia merged again, this time, with a number of states, to form the Bradenburg-Prussia, which became the Kingdom of Prussia in 1701.