The Wendish Crusade (German: Wendenkreuzzug) was an 1147 campaign, one of the Northern Crusades and also a part of the Second Crusade, led primarily by the Kingdom of Germany inside the Holy Roman Empire and directed against the Polabian Slavs (or "Wends").
By the early 12th century, the German archbishoprics of Bremen and Magdeburg sought the conversion of neighboring pagan West Slavs to Christianity through peaceful means. During the preparation of the Second Crusade to the Holy Land, however, a papal bull was issued which supported a crusade against these Slavs.
The Slavic leader Niklot preemptively invaded Wagria in June, 1147, leading to the march of the crusaders in late summer, 1147. They achieved an ostensible baptism of Slavs at Dobin and were repulsed from Demmin. Another crusading army marched on the already Christian city of Szczecin (Stettin), whereupon the crusaders dispersed upon arrival.
The Christian army, composed primarily of Saxons and Danes, forced tribute from the pagan Slavs and affirmed German control of Wagria and Polabia, but failed to convert the bulk of the population immediately.
The Ottonian dynasty supported eastward expansion of the Holy Roman Empire towards Wendish (West Slavic) lands during the 10th century. The campaigns of King Henry the Fowler and Emperor Otto the Great led to the introduction of burgwards to protect German conquests in the lands of the Sorbs. Otto's lieutenants, Margraves Gero and Hermann Billung, advanced eastward and northward respectively to claim tribute from conquered Slavs. Bishoprics were established at Meissen, Brandenburg, Havelberg, and Oldenburg to administer the territory. A great Slavic rebellion in 983 reversed the initial German gains, however. While the burgwards allowed the Saxons to retain control of Meissen, they lost Brandenburg and Havelberg. The Elbe River thus became the eastern limit of German-Roman control.
By the early 12th century, the Archbishoprics of Bremen, Magdeburg and Gniezno sought the conversion of the pagan Slavs to Christianity through peaceful means: notable missionaries included Vicelin, Norbert of Xanten, and Otto of Bamberg (sent to Pomerania by Bolesław III Wrymouth of Poland). Lacking support from the Salian dynasty of the Holy Roman Empire, secular Saxon princes seeking Slavic territory found themselves in a military stalemate with their adversaries. Christians, especially Saxons from Holstein, and pagans raided each other across the Limes Saxonicus, usually for tribute.
From 1140-43 Holsatian nobles advanced into Wagria to permanently settle in the lands of the pagan Wagri. Count Adolf II of Holstein and Henry of Badewide took control of Polabian settlements which would later become Lübeck and Ratzeburg; Vicelin was subsequently installed as bishop at Oldenburg. Adolf sought peace with the chief of the Obodrite confederacy, Niklot, and encouraged German colonization and missionary activity in Wagria.
The fall of Edessa in 1144 shocked Christendom, causing Pope Eugenius III and St. Bernard of Clairvaux to preach a Second Crusade to reinforce Outremer. While many south Germans volunteered to crusade in the Middle East, the north German Saxons were reluctant. They told Bernard of their desire to campaign against the Slavs at a Reichstag meeting in Frankfurt on 13 March 1147. Approving of the Saxons' plan, pope Eugenius issued a papal bull known as the Divina dispensatione on 13 April; there was to be no difference between the spiritual rewards of the different crusaders. Those who volunteered to crusade against the Slavs were primarily Danes, Saxons, and Poles, although there were also some Bohemians. The German monarchy took no part in the crusade, which was led by Saxon families such as the Ascanians, Wettin, and Schauenburgers. Papal legate Anselm of Havelberg was placed in overall command.
Holy war 
Upset at Adolf's participation in the crusade, Niklot preemptively invaded Wagria in June 1147, leading to the march of the crusaders in late summer 1147. After expelling the Obodrites from his territory, Adolf signed a peace treaty with Niklot. The remaining Christian crusaders targeted the Obodrite fort Dobin and the Liutizian fort Demmin.
The forces attacking Dobin included those of the Danes Canute V and Sweyn III, Archbishop Adalbert II of Bremen, and Duke Henry the Lion of Saxony. Avoiding pitched battles, Niklot ably defended the marshland of Dobin. One army of Danes was defeated by Slavs from Dobin, while another had to defend the Danish fleet from Niklot's allies, the Rani of Rügen. Henry and Adalbert maintained the siege of Dobin after the retreat of the Danes. When some crusaders advocated ravaging the countryside, others objected by asking, "Is not the land we are devastating our land, and the people we are fighting our people?" The Saxon army under Henry the Lion withdrew after Niklot agreed to have Dobin's garrison undergo baptism.
The Saxon army directed against Demmin was led by several bishops, including those of Mainz, Halberstadt, Münster, Merseburg, Brandenburg, Olmütz, and Bishop Anselm of Havelberg. While their stated goal was to achieve the conversion of the pagans, most also sought additional territory and tithe for their dioceses; Abbot Wibald of Corvey went in the hopes of acquiring the island of Rügen. The Demmin campaign also included the secular margraves Conrad I and Albert the Bear, who hoped to expand their marches. A Royal Polish contingent wanted to add to the Bishopric of Lebus. Marching from Magdeburg, Albert the Bear recovered Havelberg, lost since the 983 Slavic rebellion. The crusaders then destroyed a pagan temple and castle at Malchow. After an unsuccessful siege of Demmin, a contingent of crusaders was diverted by the margraves to attack central Pomerania instead. They reached the already Christian city Szczecin, whereupon the crusaders dispersed after meeting with Bishop Adalbert of Pomerania and Christian duke Ratibor I of Pomerania.
The Wendish Crusade achieved mixed results. While the Saxons affirmed their possession of Wagria and Polabia, Niklot retained control of the Obodrite land east of Lübeck. The Saxons also received tribute from Niklot, enabled the colonization of the Bishopric of Havelberg, and freed some Danish prisoners. However, the disparate Christian leaders regarded their counterparts with suspicion and accused each other of sabotaging the campaign.
According to Bernard of Clairvaux, the goal of the crusade was to battle the pagan Slavs "until such a time as, by God's help, they shall either be converted or deleted". However, the crusade failed to achieve the conversion of most of the Wends. The Saxons achieved largely token conversions at Dobin, as the Slavs returned to their pagan beliefs once the Christian armies dispersed; Albert of Pomerania explained, "If they had come to strengthen the Christian faith ... they should have done so by preaching, not by arms".
The countryside of Mecklenburg and central Pomerania was plundered and depopulated with much bloodshed, especially by the troops of Henry the Lion. Of Henry's campaigns, Helmold of Bosau wrote that "there was no mention of Christianity, but only of money". The Slavic inhabitants also lost much of their methods of production, limiting their resistance in the future.
See also 
- Barraclough, p. 263
- Davies, p. 362
- Herrmann, p. 326
- Herrmann, p. 328
- Christiansen, p. 55
- Christiansen, p. 53
- Christiansen, p. 54
- Herrmann, p. 327
- Barraclough, Geoffrey (1984). The Origins of Modern Germany. New York: W. W. Norton & Company. p. 481. ISBN 0-393-30153-2.
- Christiansen, Eric (1997). The Northern Crusades. London: Penguin Books. p. 287. ISBN 0-14-026653-4.
- Davies, Norman (1996). Europe: A History. Oxford: Oxford University Press. p. 1365. ISBN 0-06-097468-0.
- Herrmann, Joachim (1970). Die Slawen in Deutschland. Berlin: Akademie-Verlag GmbH. p. 530.