Menorca had passed into English hands due to the Treaty of Utrecht, but Carlos III was determined to get it back and therefore allied himself with Louis XVI of France.
The idea of the Spanish king and his ministers was to give the enemy an unexpected blow in Menorca, because in Mahón more than 80 corsairs manned with outlaws from all nations were sheltered who, authorized by the governor, Lieutenant General James Murray, captured ships that they could be doing business with Britain’s ‘enemies’, strangling trade in the Mediterranean.
Therefore, an invasion of Menorca was planned during the first months of 1781 between Luis Berton de los Blats, Duke of Crillón, and the foreign minister José Moñino y Redondo, Count of Floridablanca.
On June 25, 1781, a French squadron of about 20 warships commanded by Admiral Luc Urbain du Bouëxic, Count of Guichen, sailed from Brest. To fool the British they would not join their Spanish allies until they were close to the objective. The Spanish invasion fleet, under the command of Admiral Buenaventura Moreno, had 51 troop transports, 18 supply ships, 3 hospital ships, 3 food ships, 2 bombards, a fire ship and 13 armed escorts. He left Cádiz on July 23, 1781 and initially headed west to give the appearance that his destination was America, but, when night came, he turned around and passed through Gibraltar (July 25). Facing contrary winds in the Mediterranean, on July 29 the convoy began to break up and was forced to take refuge in the cove of La Subida, near Cartagena, where it waited for the French fleet.
The French later joined the Spanish and the combined fleet left La Subida on August 5, sighted Alicante on August 14, and on the night of August 17 moved away from the Spanish coast to sail parallel to the island of Formentera. On August 18, passing through the small island of Cabrera to the south of Mallorca, the fleet was joined by another 4 warships that came from the port of Palma. That night the wind was blowing from the southeast and the fleet had to take precautions to avoid being run aground in Mallorca, but Menorca was finally sighted the next morning. The siege of the Island was about to take place.