Ambrosian Republic

   After Filippo Maria, the last Visconti duke of Milan, died in 1447 without a legitimate heir, the citizens of Milan attempted to restore their medieval republican government, named in honor of St. Ambrose, the city's patron saint. The attempt failed, partly because of rivalries among the ruling group of wealthy families and social tension between rich and poor, but most directly because the new regime hired the prominent condottiere general Francesco Sforza to defend it. Although Sforza was an able general, he had married the illegitimate daughter of the last Visconti duke. After brushing aside the city's foreign attackers, Sforza seized control and in 1450 forced the city to surrender and accept him as duke.