King of Denmark (1157-1182), whose military expeditions against the pagan Wends established Denmark as a major sea power in the Baltic.
Valdemar, known to posterity as “the Great” (Dan. den Store), was the son of Knud Lavard, duke of Schleswig, and Ingeborg, daughter of Mstislav, prince of Kiev; he was named after his maternal great-grandfather, Vladimir II Monomakh, prince of Kiev.
Born only a week after his father’s murder in 1131, Valdemar was brought up by a Danish nobleman, one of whose sons was later the archbishop of Lund, Absalon. Following years of civil war, which opened Denmark to attacks from the pagan Wendish tribes on the southwestern shore of the Baltic Sea, Valdemar became sole ruler of Denmark in 1157. The chronicler Saxo Grammaticus recounts almost yearly crusading expeditions led by Valdemar and Absalon against the Wends in cooperation and competition with Henry the Lion, duke of Saxony. These culminated in the conquest of the pagan island of Rügen in 1168 and the submission of this region to the Danish church. After 1170 Danish crusading efforts were directed further east, against Pomerania. Valdemar was the founder of Antvorskov,the first hospital of the Order of St. John in Scandinavia, although the precise date of the foundation is unknown.
Valdemar died in 1182. A lead plate on his grave tells of a king devoted to conquering and converting the Wends. He was married to a Russian princess, Sophia of Minsk (d. 1198). Of his seven children, two legitimate sons, Knud VI (d. 1202) and Valdemar II (d. 1241), became kings of Denmark.