Imperial ban
At the 1125 "Hoftag" diet in Regensburg, the king officially requested the surrender of the Salian possessions. After he imposed an Imperial ban on the Hohenstaufens, a conflict erupted between Frederick and his supporters, and Lothair: encouraged by Archbishop Adalbert and several princes, the king occupied Hohenstaufen lands in Upper Lorraine and Alsace. However, an attack by Welf forces on the Swabian core territory failed, like the siege of Nuremberg by Lothair in 1127. Frederick relieved the siege and moreover gained the support from his brother Conrad, who had just returned from a pilgrimage to the Holy Land. During the fighting, Frederick lost an eye, whereafter he was no longer eligible as German king.