The Spanish blockade was to be directed by Martín Álvarez de Sotomayor. Spanish ground forces were composed of 16 infantry battalions, which included the Royal Guards and the Walloon Guards, along with artillery and 12 squadrons of cavalry. This yielded a total of about 14,000 men. The artillery was commanded by Rudesindo Tilly, while the cavalry and the French dragoons were headed by the Marquis of Arellano. Antonio Barceló commanded the maritime forces responsible for blockading the bay. He established his base in Algeciras, with a fleet of several xebecs and gunboats. French involvement was limited, but in 1781 the first of them arrived in numbers with the Régiment de Besançon (Half Company of artillery).