At the end of 1166 the emperor went to Italy for the fourth time at the head of a powerful army. To avoid the Marca of Verona, after having crossed the Alps from the Brenner Pass, instead of going along the usual Adige valley, Barbarossa turned towards Val Camonica; its objective was not, however, the attack on the rebellious Italian communes, but the Papacy. In fact, Frederick sided with the Antipope Paschal III, who in the meantime had ousted the legitimate pontiff, Alexander III, from Peter's throne; the latter, in 1165, after having obtained the recognition of the other European sovereigns, had returned to Rome, but Barbarossa, mindful of the role that his predecessors had on papal appointments, decided to intervene directly. As a test of strength, and for demonstration purposes, Frederick attacked some cities in Northern Italy, reaching Rome victorious, but an epidemic that spread among the ranks of the imperial army (perhaps of malaria) and which also affected the emperor himself, forced him to leave Rome, which in the meantime had surrendered, and to return precipitously to Northern Italy in search of reinforcements (August 1167).