Political conflict broke out across the Empire shortly after the marriage, triggered when Henry arrested his chancellor, Archbishop Adalbert of Mainz, and various other German princes. Rebellions followed, accompanied by opposition from within the Church, which played an important part in administering the Empire, and this led to the formal excommunication of the Emperor by Pope Paschal II. Henry and Matilda marched over the Alps into Italy in early 1116, intent on settling matters permanently with the Pope. Matilda was now playing a full part in the imperial government, sponsoring royal grants, dealing with petitioners and taking part in ceremonial occasions. The rest of the year was spent establishing control of northern Italy, and in early 1117 the pair advanced on Rome itself.