In February 1026, Conrad assembled a large army of armored knights for an expedition into Italy, including troops commanded by both Archbishop Aribo of Mainz and Archbishop Pilgrim of Cologne. Conrad's army moved south and a contingent besieged Pavia and blocked all trade in the area, as he continued his campaign. By March 1026, Conrad arrived in Milan and was crowned with the Iron Crown of the Lombards by Archbishop Aribert of Milan as King of the Lombards. From Milan, Conrad traveled to Vercelli, where he celebrated Easter with the aged Bishop Leo of Vercelli, who had been a chief advisor to the late Emperor Otto III. When Leo died a few days later, Archbishop Aribert became the chief supporter of the Salian dynasty in Italy. With Conrad's assistance, Aribert rose to highest ranking religious office in Italy and oversaw the expansion of the Basilica of Sant'Ambrogio in Milan. In June 1026, Conrad lead his army to Ravenna, but quartering his soldiers among the Ravennese population caused tensions in the city. Conrad then marched north to mitigate the risk the summer heat might pose to his army. In autumn Conrad left his summer camp in the Po valley and marched to the Burgundian border. Conrad then celebrated Christmas at Ivrea. By the end of winter, the Italian aristocrats voluntarily ended their opposition to Conrad's reign. Pavia, however, remained in revolt until early 1027 when Abbot Odilo of Cluny brokered a peace deal between the city and Conrad.