Vigevano was a Ghibelline township, favoring the Emperor and was therefore invaded and taken by the Milanese in 1201 and again in 1275. In 1328 it finally gave itself up to Azzone Visconti, after which it shared the fortunes of Milan. The Church of S. Pietro Martire (St. Peter Martyr) was built, with the neighbouring Dominican convent, by Filippo Maria Visconti in 1445. In the last years of Visconti's control it kept a siege by Francesco Sforza. Once he was settled in power in Lombardy, Sforza secured the erection of Vigevano as the seat of a bishop and provided its revenues.