Voltaire wrote a satirical account of the raid at which Hume himself was personally in attendance with General St Clair. However, it is difficult to find out if Voltaire was actually an eyewitness also, or if his accounts were second hand.
Meyer, Paul H. 1951. “Voltaire and Hume’s Descent on the Coast of Brittany.” Modern Language Notes 66 (7): 429–35. doi:10.2307/2909982.
Neither source mentions if Francois-Marie Arouet (Voltaire) was present at the engagement, and it is difficult to find any mention of it in Voltaire's biographies available on line.
Further research (still no conclusion as yet):
From Chateau de Cirey
From the SEP
From Ernest Mossner's The Life of David Hume
Primary Sources and Older Commentaries
- Condorcet, marquis de, Jean-Antoine-Nicolas de Caritat. 1792. The Life of Voltaire: By the Marquis de Condorcet. To Which Are Added Memoirs of Voltaire, Written by Himself. Translated from the French. In Two Volumes. Vol. I[-II]. Philadelphia: Printed by and for W. Spotswood.
- Duvernet, abbé. 1787. The Life of Voltaire; with Notes Illustrative and Explanatory: Translated from the French, By G.P. Monke, Lieutenant in the Navy. London: Printed for T. Becket, in Pall-Mall, bookseller to His Royal Highness the Prince of Wales, and their Royal Highnesses the Princes.
- Tiedeman, H. 1870. “Voltaire’s Farewell to Holland.” Notes and Queries s4–V (129): 581.
- Voltaire. 1784. Memoirs of the Life of Voltaire: Written by Himself. Translated from the French. London: printed for G. Robinson, No 25, Pater-Noster-Row.
- Voltaire. 1990. The Complete Tales of Voltaire. New York: H. Fertig.
- Aldridge, Alfred O. 1976. Voltaire and the Century of Light. Princeton, N.J: Princeton University Press.
- Darnton, R. 2015. “Voltaire, Historian.” RARITAN-A QUARTERLY REVIEW 35 (2): 20–28.