Henry was a loyal supporter in the warfare between his father-in-law King Lothair and the Hohenstaufen brothers, Duke Frederick II (who was Henry's brother-in-law, having been married to his sister
Judith) and Conrad, then duke in
Franconia and
anti-king of Germany. While engaged in this struggle, Henry was also occupied in suppressing a rising in Bavaria, led by Count Frederick of
Bogen, during which both duke and count sought to establish their own candidates as
bishop of Regensburg. After a war of devastation, Count Frederick submitted in 1133, and two years later the Hohenstaufen brothers made their peace with Emperor Lothair. In 1136, Henry accompanied his father-in-law to
Italy, and taking command of a Bavarian division of the Imperial army marched into the south Italian
Kingdom of Sicily up to
Bari, devastating the land as he went. Having distinguished himself by his military abilities during this campaign, Henry was appointed as margrave of
Tuscany, succeeding
Engelbert III of Sponheim, and as Lothair's successor in the Duchy of Saxony. He was also given the private properties of late Margravine
Matilda of Tuscany from the hands of
Pope Innocent II. When Emperor Lothair died on his way back from Italy in December 1137, Henry's wealth and position made him a formidable candidate for the German crown. According to the contemporary chronicler
Otto of Freising, after his appointment as Duke of Saxony he boasted of a realm stretching "from sea to sea, from Denmark to Sicily". However, the same qualities which earned him the
cognomen of "the Proud" aroused the jealousy of the
princes and so ultimately prevented his election. The new king, Conrad III, demanded the
Imperial Regalia which Henry had received from Lothair, and the duke in return asked for his investiture with the Saxon duchy. But Conrad, who feared his power, refused to assent to this on the pretext that it was unlawful for two
duchies to be in one hand. Attempts at a settlement failed, and when in July 1138 Henry refused to take the oath of allegiance, he was
banned and deprived of both his duchies. Bavaria was given to the
Babenberg margrave
Leopold IV of Austria, a half-brother of the new king Conrad. Saxony, which he had attempted to hold but was not officially invested with, was given to the
Ascanian count
Albert the Bear, son of
Eilika of Saxony, a younger daughter of the last Billung duke Magnus. ==Death and aftermath==