Valdemar was born in 1131. His father was Canute Lavard, the only legitimate son of Eric I Evergood. Canute was very popular and was the first Duke of Schleswig, but was killed by his cousin Magnus I of Sweden shortly before Valdemar was born. Magnus was the son of King Niels of Denmark. Valdemar was raised with Absalon who became a lifelong friend.
Eric I had two illegitimate children, Eric II the Memorable and Ragnhilde who became the mother of Eric III Lamb. When Eric III (Valdemar’s cousin) abdicated in 1146 a civil war broke out with three claimants to the throne: Valdemar, Sweyn III Grathe (son of Eric II) and Canute V (son of Magnus I of Sweden, grandson of Niels).
The civil war lasted about 10 years and was devastating to Denmark. In 1157 the three claimants decided to settle the conflict by dividing the country among themselves. Sweyn hosted a banquet at Roskilde where he attempted to kill Canute, Valdemar and Absalon. Canute was killed, but Valdemar and Absalon escaped. This is often referred to as the “Bloodfeast of Roskilde.”
After making his escape, Valdemar fled to Jutland with Sweyn in pursuit. They met at the Battle of Grathe Heath (23 October 1157) which Valdemar won and Sweyn was killed.
Now that Valdemar was the undisputed ruler of Denmark, the first priority was to restore order and peace to the kingdom. Valdemar’s friend and advisor Absalon became the Bishop of Roskilde in 1158. Together they made war on the Wends, who had been raiding Denmark from Pomerania and the island of Ruegen. In 1168 the Wends capital of Arkona (on Ruegen) fell and the Wends became Christian and submitted to Denmark. Thus Denmark’s influence was extended into Pomerania.
Valdemar married to Sophia of Minsk, who was a half-sister of Canute V. They had nine children including Canute VI and Valdemar II the Victorius.
Valdemar died in 1182.