Which courtier to the Roman family of the city-state of Mantua wrote a guide that describes how a courtier should act while serving at court

Baltasar Castiglione.

He wrote "Il Cortegiano" ("The Courtier") and it was his most important work.

In the manuscript, he exposes the ways in which Gentlemen has to behave in several areas; from being skilled with weapons, to writing letters correctly and also on how to properly address to other people, especially women.

It refers to a model of a Gentleman that responds to the concerns, ideals and visions of the time (Renaissance).

Baldassare Castiglione