The disorder in Germany after the fall of the Hohenstaufen afforded an opportunity for Rudolph to increase his possessions.
He was attached to the Hohenstaufen by the marriage of his daughter, Elizabeth, with Conrad, son of Frederick II.
He was the uncle and guardian of Conradin of Hohenstaufen, whom he assisted to make his journey to Italy in 1267, and accompanied as far as Verona.
Having married Constance, daughter of Manfred of Beneventum, he came forward as the representative of the claims of the Hohenstaufen in Naples and Sicily against Charles, duke of Anjou.
But the duchy was re-established after the death of the German king Henry I., and became hereditary in the Hohenstaufen family, and then in the house of Austria, which succeeded in 1273 to the imperial dignity.