[2] Already on 28 February 1689, with his tonsure, Benedetto Erba entered in the clerical state, and he was ordained deacon on 11 October 1711 and Priest a week later.

He was appointed Titular archbishop of Thessalonica on 18 December 1711, and on 3 January 1712[2] consecrated bishop in Rome by Cardinal Fabrizio Paolucci.

[1] As Archbishop of Milan he focused on pastoral activities, taking as examples Saint Charles Borromeo and Pope Innocent XI.

[5] In 1716 Benedetto Erba obtained from Pope Clement XI that the ordinary canon priests of the Cathedral of Milan could wear the white damask mitre in solemn celebrations.

Even if under his reign the Duchy of Milan passed from the Spanish Empire to the Habsburg monarchy, Benedetto Erba succeeded in maintaining good relations with all the political powers.