Waldemar II, 1170–1241, king of Denmark (1202–41), second son of Waldemar I. In the reign of his brother, Canute VI, he defended Denmark from German aggression and then extended Danish control over Schwerin. After his accession, the king of Norway paid him homage (1204). When his German conquests had been confirmed (1214) by Frederick II, the German king, he undertook a crusade against the Estonians and became master of much of the Baltic region. In 1223 he was treacherously seized by his vassal the count of Schwerin and held prisoner for three years. He was released only after he had been forced to relinquish much of his territory. He then attempted a reconquest, but was defeated (1227) at Bornhöved and spent the remainder of his life in codifying Danish law and in forwarding internal reform. He was succeeded by his son, Eric IV.