Wichmann von Seeburg (c. 1115 – 25 August 1192) was the Bishop of Naumburg (Zeitz) from 1150 until 1154 and Archbishop of Magdeburg from 1152 until his death. He was the son of Gero, Count of Seeburg. During his long career, he was an unflappable supporter of Frederick Barbarossa against Pope Alexander III and an implacable military leader against the emperor's foes in the northeast, especially Henry the Lion.
Wichmann studied theology at the University of Paris before becoming a canon in Halberstadt. He was made Bishop of Zeitz-Naumburg in 1150 and was quickly appointed to the archdiocese of Magdeburg by the newly-crowned Frederick Barbarossa in 1152. He immediately endeavoured to extend his diocese and its economy; he actively promoted trade within the cities. In 1157, he teamed with Albert the Bear to Germanise the cities of Brandenburg and Jüterbog, whose vicinity he conquered and granted to the Cistercian monastery of Zinna in 1180.
In 1164, he undertook a pilgrimage to Palestine and fell for a time into Turkish hands. In 1166, he joined the other princes in war with Henry the Lion, but he succeeded only in seeing his lands devastated. In 1175, he supplied auxiliaries to the emperor for his Italian campaign. He was in Venice negotiating the peace treaty in 1177. In 1178, he was back in Saxony for the war against Henry the Lion. He strongly worked for Henry's removal (1181) and greatly profited from its actualisation, becoming the principal secular authority in Saxony after. He remained deeply predisposed against the Welfs, however.
In 1180, he gave a part of his extensive possessions to Seitenstetten Abbey in Austria.
He died on 25 August 1192 in the proximity of Köthen and was buried in his own cathedral. The city and diocese of Magdeburg had fully bloomed under his oversight.
| Preceded by Gunther II |
Bishop of Naumburg 1150–1154 |
Succeeded by Berthold I |
| Preceded by Frederick I |
Archbishop of Magdeburg 1152–1192 |
Succeeded by Ludolf |