Vratislav I , Duke of Bohemia 's father was ,Borivoj , Duke of Bohemia, who acceeded in 870 and died in 895. Vratislav's brother was Spyithnev , King of Bohemia.
Vratislav I had a son named ,Boleslav I the Cruel, Duke of Bohemia, who acceeded in 929 and died in 972 .