On his return journey in 1148 Welf had entered into an alliance with Roger II of Sicily, Conrad's enemy.

[2][3][4] Having agreed to foment discord in Germany, he revived the Welf claim to the Duchy of Bavaria for his nephew, Henry the Lion.

[5] Henry's forward reconnaissance troops surprised the Welfs at the royal castle (castrum regis) of Flochberg (Vlochperch), near Nördlingen, as they were retreating from Swabia and pinned them down.

[6] At the same time, Conrad was besieging Brunswick in the Duchy of Saxony, but he lifted the siege when confronted by Henry the Lion.

The military prowess of Henry (VI) was emphasised in letters to his uncle, the Byzantine emperor Manuel I, Conrad's ally and Roger II's enemy, but the young king died later that year.