Sweyn was born in Denmark, a son of the Danish king Sweyn Estridsen, and husband of Florine of Burgundy. He is famous for his participation in the First Crusade, which he primarily spent fighting the Turks. On his way to Jerusalem in 1097, he and 1,500 other Danish knights were attacked by the Turks. The Danes lost the battle, and Sweyn the Crusader was killed.