[1] Among the scant information about his life, it is known that in 679 he organized and held a synod with his suffragan bishops in Milan in order to condemn the Monothelite doctrine.

[1] According to Paul the Deacon this synod issued a letter, written by a Damian later bishop of Pavia, directly to Emperor Constantine IV.

[2] A year later Mansuetus and his suffragan bishops participated in Rome to a synod opened by Pope Agatho on 27 march 680 and subscribed the acts there issued.

This 680 Rome synod was held in preparation of the Third Council of Constantinople, which a few months later condemned the Monothelitism.

[2] A late tradition, with no historical basis, associates Mansuetus with the Roman family of the Savelli.