Frederick I, Duke of Swabia


Frederick I was Duke of Swabia from 1079 to his death, the first ruler from the House of Hohenstaufen.

Life

He was the son of Frederick of Büren, Count in the Riesgau and Swabian Count Palatine, with Hildegard of Egisheim-Dagsburg, a niece of Pope Leo IX and founder of the Abbey of Saint Faith in Schlettstadt, Alsace. When Frederick succeeded his father, he had Hohenstaufen Castle erected on the eponymous mountain in the Swabian Jura range, which became the ancestral seat of the dynasty. He also founded a Benedictine abbey at the site of former Lorch Castle about 1100. By his mother he ruled over large Alsatian estates around Schlettstadt and Hagenau.
When during the Investiture Controversy the Swabian duke Rudolf of Rheinfelden was elected anti-king to King Henry IV of Germany, Frederick remained a loyal supporter of the ruling Salian dynasty. In turn Henry vested him with the Swabian ducal dignity in 1079 and also gave him the hand of his seven-year-old daughter Agnes of Waiblingen. Contested by Rudolf's son Berthold of Rheinfelden and Berthold of Zähringen, Frederick only ruled over the northern parts of the Swabian duchy down to Ulm and the Danube River. Finally in 1098, he and Berthold of Zähringen reached a compromise, whereby his rival confined himself to the title of a "Duke of Zähringen".
In the last years of his reign, Frederick was able to expand the Hohenstaufen territories northwards, when he assumed the office of a Vogt of Weissenburg Abbey and the Bishopric of Speyer in Rhenish Franconia.

Marriage and issue

About 1086/87, Frederick married Agnes, daughter of Emperor Henry IV. They had several sons and daughters, amongst whom were:
After Frederick's death, Agnes secondly married the Babenberg margrave Leopold III of Austria in 1106. Both are buried in Klosterneuburg Monastery.