Vivaldi's oratorio Juditha triumphans is not only a musical military exercise (it is indeed explicitly called "Sacrum militare oratorio") during the Turkish siege of Corfu in 1716, which was delicate for Venice, but also an impressive performance show of the vocal and instrumental possibilities of the Ospedale della Pietà. The orchestra comes up with an extraordinary wealth of instruments, some of them unusual, even by Vivaldi's standards: Chalumeau, two clarinets, four theorbos, viola d'amore and mandolin, among others, are called for.