Governor Murray began the defense of San Felipe Castle with two objectives: to await the arrival of a relief convoy and to hold out as long as possible to help his comrades in Gibraltar. The defense comprised the Castle itself; to the south, separated by Cala San Esteban, was Fort Malborough and, to the north, Torre Felipet, from where the entrance to the port of Mahón was closed by a chain that joined the castle of San Felipe.
To facilitate the transport of the war supplies unloaded in Sa Mesquida, a path was opened for carts from the beach to the port of Mahón, and a wooden jetty was also built.
Once the tents arrived from Barcelona were distributed, the camp was organized by brigades and a total of 11 batteries and 33 mortars manned by 931 men were installed in various locations.
The Duke of Crillon requested more soldiers and on 23 October the French infantry regiments from Lionois, Bretagne, Royal-Suèdois and Bouillon arrived with a total of 3,886 men. 7 days later, on October 30, the French brigade arrived in Mahón with the Bretagne and Lionois regiments.