army, the sources are conflicting. The chronicles of Boso Breakspeare report in fact that the crossing of the two armies took place at half a mile (about 700 m) from the Carroccio: The annals of Piacenza instead report that the contact occurred near Milan: As regards the exact location of the Carroccio in reference to the current topography of Legnano, one of the chronicles of the clash, the Cologne Annals, contain important information: This would suggest that the Carroccio was located on the edge of a steep slope flanking the Olona, so that the imperial cavalry, whose arrival was expected along the river, would have been forced to attack the center of the League's army Lombard climbing up the escarpment. Considering the evolution of the clash, this could mean that the crucial phases in defense of the Carroccio have been fought on the territory of the Legnanese contrada of San Martino (more precisely, near the 15th century church of the same name, which in fact dominates a slope that descends towards the Olona) or of the Legnanese quarter of Costa San Giorgio, since in another part of the neighboring areas it is not possible to identify another depression with the characteristics suitable for its defense. Considering the last hypothesis mentioned, the final clash could also have taken place on part of the territory now belonging to the Legnanese contrade of Sant'Ambrogio and San Magno (between the quartier of "Costa of San Giorgio" and the Olona is still present today a steep slope: this slope was later included in the Parco castello) and to the municipality of San Giorgio su Legnano. A popular legend tells that at that time a tunnel put San Giorgio su Legnano in communication with the Visconti castle of Legnano and that for this tunnel Frederick Barbarossa managed to escape and save himself after the defeat. Towards the end of the 20th century, during some excavations, sections of a very ancient tunnel were actually found: the first was found not far from San Giorgio su Legnano, while the second section was discovered in Legnano. Both were immediately blocked by the municipal administration for security reasons. During some excavations carried out in 2014 at the Visconti castle in Legnano, the entrance to another tunnel was identified. Aftermath The battle of Legnano put an end to Frederick Barbarossa's fifth descent in Italy and his attempt to hegemonize the municipalities