The
Atlantic campaign of 1806 was a complicated series of manoeuvrees and counter-manoeuveres conducted by squadrons of the
French Navy and the British
Royal Navy across the Atlantic Ocean during the spring and summer of 1806, as part of the
Napoleonic Wars. The campaign followed directly from the
Trafalgar campaign of the year before, in which the French Mediterranean fleet had crossed the Atlantic, returned to Europe and joined with the Spanish fleet. On 21 October 1805, this combined force was destroyed by a British fleet under
Lord Nelson at the
Battle of Trafalgar, although the campaign did not end until the
Battle of Cape Ortegal on 4 November 1805. Believing that the French Navy would not be capable of organised resistance at sea during the winter, the
First Lord of the Admiralty Lord Barham withdrew the British blockade squadrons to harbour. Barham had miscalculated – the French Atlantic fleet, based at
Brest, had not been involved in the Trafalgar campaign and was therefore at full strength. Taking advantage of the reduction in the British forces off the port,
Napoleon ordered two heavy squadrons to sea, under instructions to raid British trade routes while avoiding contact with equivalent Royal Navy forces.