Milan assumed a central role in the movement for autonomy that developed in the 11th century as a reaction against the control of the German emperors. The city-state was born, an expression of the new political power of the city and its will to fight against all feudal powers. The city was governed by democratic rule. This is the period of Palazzo della Ragione, located in the present-day Piazzale dei Mercanti.
The city became richer and with a population of 100,000 experienced a boom in development thanks to the trades of metalworking, textiles, crafts, agriculture and animal breeding. Traffic and trade grew significantly with the city’s construction of a dense network of urban canals.
It didn’t take long for the City States to begin fighting each other to try to limit neighbouring powers. The Milanese destroyed Lodi and continuously warred with Pavia, Cremona and Como, who in turn asked the Emperor of Germany, Frederick I Barbarossa for help.
Federico declared war on the City of Milan and her allies six times in all. During the first expedition Tortona was destroyed; in the second Milan itself was forced to surrender. In 1160 Barbarossa returned to Italy and surrounded the city of Milan which had previously risen up against the Lord that had been sent by the emperor to govern it. After two years of heroic opposition, a fire destroyed the storehouses containing the entire food supply: within just a few days the city was forced to surrender.
A period of peace followed, during which Milan rebuilt the basilicas destroyed by the Germans and put up new churches and palaces.