the emperor together with another area of Lombardy, the Martesana. The Lombard League troops took possession of the area between Legnano, Busto Arsizio, and Borsano. The remaining part of the army, which on the whole was formed by about 15,000 men (3,000 of whom were knights, while 12,000 were infantry), followed with considerable detachment along the road between the Lombard capital and Legnano. The decision to place the Carroccio in Legnano was not accidental. At the time the village represented an easy access for those coming from the north to the Milanese countryside, given that it was located at the mouth of the Valle Olona, which ends at Castellanza; this passage had therefore to be closed and strenuously defended to prevent the attack on Milan, which was also facilitated by the presence of an important road that existed since Roman times, the Via Severiana Augusta, which connected Mediolanum (the modern Milan) with the Verbanus Lacus (Lake Verbano, or Lake Maggiore), and from there to the Simplon Pass (lat. Summo Plano). His journey was then taken up by Napoleon Bonaparte to build the Simplon state road. For this reason, in Legnano there was a high medieval fortification, the castle of the Cotta, which was built at the time of the Hungarian raids and which was later used during the Battle of Legnano as a military outpost. Later, the castle of the Cotta was replaced, as a defensive bulwark of Legnano, by the Castle Visconteo, which rises further south along the Olona. The Cotta castle was flanked by a defensive system formed by walls and a flooded moat that encircled the inhabited center, and by two access gates to the village: medieval Legnano thus appeared as a fortified citadel. A second reason that explains the positioning of the Carroccio in Legnano lay in the fact that the Legnanese was a territory not hostile to the troops of the Lombard League, given that the population of the area was still mindful of the devastation operated by Frederick Barbarossa a few years earlier; these people would also have provided logistical support to the troops of the League. From a strategic point of view, in Legnano the municipal army was therefore in a position that would have prevented the emperor from making the most logical moves: to attack Milan or reach Pavia. The first contact between the armies in Borsano After spending the night in