1782 was a momentous year in the life of Marianna Martines: a year of musical fulfillment, personal tragedy, and financial gain. Vienna's Tonkünstler-Sozietät performed her oratorio Isacco figura del Redentore in its two concerts during Lent, on March 17 and 19. For the first and probably only time in her life she had the opportunity to present a major work in a completely public setting, in which her music could be compared with that of Vienna's leading professional composers. About three weeks later Metastasio died at the age of eighty-four. His death left her without the man who had been her teacher, mentor, and friend since childhood, but with an inheritance of 20,000 Gulden that allowed her to live the rest of her life in reasonable comfort.

The Tonkünstler-Sozietät and Its Oratorios

In 1771 Florian Gassmann, Hofkapellmeister and music director of the Italian opera, founded an organization to raise money for the support of the widows and orphans of Vienna's professional musicians. The Tonkünstler-Sozietät usually gave four fundraising concerts a year—two during Lent and two during Advent—to which its members were expected to donate their services as performers. The society assembled a large chorus and orchestra for its concerts, which during the first two decades of its existence usually consisted of an Italian oratorio and a concerto played between the oratorio's two parts.

Gassmann helped to establish many of the society's early traditions with the composition of Betulia liberata for the first Tonkünstler-Sozietät concert, during Lent 1772. He chose a libretto by Metastasio, which, like his other oratorio texts, presents a biblical drama in which dialogue in versi sciolti (blank verse that the librettist expected to be sung in recitative) is punctuated with a series of arias. Choruses are few; the most important of them are at the end of each of the oratorio's two parts. Gassmann took full advantage of the large orchestral forces made possible by the society's bylaws to produce a score of extraordinary instrumental richness, with an orchestra that included four horns and pairs of trumpets, trombones, flutes, oboes, clarinets, and English horns. With vast amounts of orchestrally accompanied recitative he made sure that the string players who contributed their services were rarely idle. Gassmann's oratorio was first performed on March 29, 1772, by an orchestra of 200.