The Sonata Op. 61 ‘Élégie harmonique’ was written after the death of Dussek's patron, Prince Ferdinand of Prussia, at the battle of Saalfeld on 10 October 1806. First published by Pleyel in Paris the following year, the sonata is infused with a spirit of lament and conveys great intensity of emotion. With its almost exclusive focus on minor keys and its increasingly relentless pace, the work stands out among the sonatas of the classical period.