Henry married Welf to Uta, the daughter of Godfrey of Calw, count palatine of the Rhine.

When Conrad III of Germany, Frederick's uncle, confiscated the duchy of Bavaria in 1142, Welf joined his brother in rebelling.

In October 1152, at Würzburg, Frederick gave Welf, as the head of his family, the duchy of Spoleto, margraviate of Tuscany, and principality of Sardinia among other Italian properties.

Welf remained in charge of his Italian duchies until 1173, while Christian, Archbishop of Mainz, was imperial vicar.

The male line of Welfs, descended from Henry the Lion, remained with their Billung patrimony in northern Germany.