On 10 November 1808, under capitaine de frégate Rousseau, Junon departed Cherbourg for Martinique, along with Vénus, Amphitrite, Cygne and Papillon.

[1] Her repairs completed, Junon returned to the Caribbean in September 1809 under the command of Captain John Shortland, under orders to enforce a naval blockade of French-controlled Guadeloupe.

[2] At 2.15pm on 13 December, Junon was in company with the 14-gun sloop-of-war HMS Observateur when her crew sighted four unknown ships heading west towards the French colony.

[2] At 5.50pm, when Junon was "within Half Pistol Shott"[3] of the lead frigate, that vessel suddenly hauled down its Spanish and British flags and raised the French ensign.

Junon herself received broadsides to her port, starboard, and stern and quickly became indefensible; her crew surrendered at 7pm when French soldiers boarded their ship.

[4][a] The British sloop Observateur had fired upon the French when the engagement began but Junon's capture was too swift for her to directly assist her sister ship.

[2] The French vessels were the frigates Clorinde and Renommée, and the lightly armed flûtes Loire and Seine, en route to Guadeloupe with supplies and reinforcements for the colony.

However, when Junon and Observateur drew near, Roquebert decide to continue with the ruse of the false flag to lure the British into range of all four French vessels at the same time.