Between 1665 and 1675 he spent most of his time in Hanover, where he held the post of Kapellmeister to Duke Johann Friedrich of Brunswick-Lüneburg – returning frequently to Venice to compose operas for the Carnival.
The duke had met Sartorio upon one of his four visits to Italy, one of which was for the purpose of lending the Republic of Venice substantial military aid against the Turks.
Sartorio began his duties as Kapellmeister on Trinity Sunday 1666 not too long after the Duke's new palace in Herrenhausen near Hanover was finished.
In addition, the group's repertory included masses, motets and psalms by Henri Dumont, Bonifatio Gratiani and Orazio Tarditi.
Sartorio worked in Hanover up until 1675, during which time he returned frequently to Venice in the winter, both to compose operas for Carnival and to hire musicians for service at court.
Originally the librettist, Nicolò Minato, had intended for the two works to be performed on successive evenings, but it appears that either Sartorio or the theatre management overturned this decision.
Sartorio was supposed to return to Hanover at the end of the season in which L'Adelaide premiered, but poor health prevented him from travelling.
He was further motivated to stay by an invitation to write one of two operas to be performed at the Teatro di San Luca during the next Carnival season.
Sartorio thereupon offered L'Orfeo, a variation on the myth of Orpheus and Eurydice with comic interludes and elaborate sub-plots featuring such incongruous characters as Hercules, Achilles, and Thetis.
The Teatro San Angelo had commissioned La Flora, and not wanting to give it up, hired Marc'Antonio Ziani to finish it.