Who dated Rosalie Levasseur?

Marie-Rose-(Claude-)Josephe Levasseur (or Le Vasseur), known in her day as Mademoiselle Rosalie, and later commonly referred to as Rosalie Levasseur (8 October 1749 – 6 May 1826) was a French soprano who is best remembered for her work with the composer Christoph Willibald Gluck.

Florimond Claude, comte de Mercy-Argenteau (20 April 1727 – 25 August 1794) was an Austrian diplomat, statesman of French noble ancestry, in the service of the Holy Roman Empire.