The campaign was to be carried out by the Army of Estremadura, under the Duke of Alburquerque's much depleted force of 8,000 infantry and 1,500 cavalry, as he had had to transfer three divisions of infantry and twelve regiments of cavalry to reinforce the Army of La Mancha, under Venegas, and which, after its defeat at Almonacid, had been reduced to only 25,000 men.