Frederick VI of Hohenstaufen was duke of Swabia from 1170 to his death at the siege of Acre. He was the third son of Frederick III Barbarossa and Beatrice I, Countess of Burgundy and brother of Henry VI, Holy Roman Emperor. Frederick married (or only bethroted) with the princess Constanze of Hungary, but had no known descendants. See also: Dukes of Swabia family tree Wikipedia
The definitive Wikipedia entry for Frederick VI, Duke of Swabia. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Frederick_VI,_Duke_of_Swabia
The definitive Wikipedia entry for Frederick VI, Duke of Swabia. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Frederick_VI%2c_Duke_of_Swabia