The conviction that the ‘deposition faction’ was divided by the enmity of Welf IV and Otto of Northeim doubtless persuaded Henry IV that it was safe to proceed with his Italian expedition. As the spring of 1081 approached, his preparations for departure concentrated on the securing of the south-eastern frontier of the German kingdom. On the eve of the king's Italian expedition Margrave Leopold II of Austria rebelled again at the instigation of the papal legate, Altmann of Passau. Henry's response was to confer the march of Austria on Duke Vratislav II of Bohemia. This indispensable ally was now entrusted with the defence of the whole eastern frontier: to his responsibility for the Saxon marches of Meissen and Lower Lusatia was added that for the eastern frontier of Bavaria. Vratislav's son, Borivoi, was to accompany Henry on the Italian expedition of 1081 (and also on those of 1082–4). Since many knights remained behind to secure the German kingdom, Henry's army consisted ‘partly of his own forces, partly of mercenaries or common soldiers’.

Entering Italy by the Brenner Pass in March, the army moved rapidly, reaching Verona by Easter (4 April). Ten days later Henry was in Milan; early in May he reached Ravenna. Turning aside from the direct route to Rome, he sought advice and military assistance from Wibert of Ravenna.