Lamellerie's expedition was a French naval operation launched in February 1806. Four French Navy frigates and a brig, all survivors of the Battle of Trafalgar in October 1805, attempted to break past the British blockade of Cadiz on 23 February 1806, taking advantage of the withdrawal of the principal blockade squadron several months earlier at the start of the Atlantic campaign of 1806. Although the squadron was intercepted by elements of the British blockade force, Captain Louis-Charles-Auguste Delamarre de Lamellerie escaped with the four frigates by abandoning the slower brig, which was captured. During the next six months, Lamellerie's squadron cruised the Atlantic, visiting Senegal, Cayenne and the West Indies but failing to cause any significant disruption to British trade.
On 27 July, as the squadron neared Rochefort, it was spotted by HMS Mars, a Royal Navy ship of the line stationed off the port to intercept French ships entering or leaving. Signalling to the rest of the British squadron, Captain Robert Dudley Oliver took Mars in pursuit, chasing the French squadron all through the night and into the next morning, by which time the frigate Rhin had fallen far behind the others. Recognising that Rhin was in danger of being captured, Lamellerie turned back to her defence with his main squadron but then changed his mind, turning once more and retreating to Rochefort as Oliver took possession of the heavily outgunned Rhin.
Background
On 21 October 1805, the French and Spanish allied fleet was almost destroyed at the Battle of Trafalgar by a Royal Navy fleet under Vice-Admiral Lord Nelson. Among the scattered survivors of the Allied fleet were five French frigates, untouched during the action. With the rest of the surviving ships, the frigates anchored in Cadiz during the week that followed the battle and remained there for the rest of the year, contained in the harbour by a large British blockade squadron led by Vice-Admiral Sir John Thomas Duckworth. In December 1805 however, Duckworth abandoned the station in search of a French squadron under Vice-Admiral Zacharie Allemand that was raiding British convoys off the Savage Islands. Although Allemand escaped Duckworth, the British admiral became embroiled in the Atlantic campaign of 1806 and did not return to Cadiz, eventually sailing to the Caribbean where he won the Battle of San Domingo on 6 February 1806. In his absence, Duckworth's squadron was replaced at Cadiz by ships grudgingly despatched from the Mediterranean Fleet, under the command of Vice-Admiral Lord Collingwood.
The French Navy was concerned about its ships trapped in Cadiz and sought to bring them back to French harbours, particularly to make up for the heavy losses suffered in the Trafalgar Campaign. Therefore, four frigates and a brig were prepared for sea under the most senior frigate captain, Captain Louis-Charles-Auguste Delamarre de Lamellerie of Hortense. These ships were to break out of Cadiz, conduct a six-month raiding mission in the Atlantic to distract attention from the ongoing Atlantic campaign, and raid British merchant shipping. At the conclusion of the six months, Lamellerie was to return to Rochefort to join the French Atlantic Fleet.
Breakout
Word of Lamellerie's preparations reached Collingwood, and he planned a ruse to lure the French frigate squadron out into open water. Withdrawing all the large vessels of the blockade squadron, Collingwood kept only the 36-gun frigate HMS Hydra and the 18-gun sloop HMS Moselle in position to create the impression that the principal blockading force had been driven off. This it was hoped would draw Lamellerie into an attack on the lone ships that would allow the rest of Collingwood's squadron, hidden just beyond the horizon, to counterattack and annihilate the French squadron. However, on 23 February a strong westerly wind blew up and the main squadron, Hydra and Moselle were all blown too far to the east. This was spotted by lookouts on shore and Lamellerie took the opportunity to leave port on 26 February, while the British ships were still out of position.