Dupont's force was increased as he advanced, till it amounted to 20,000 men; and with these he took possession of Baylen and La Carolina, in Andalusia, and stormed Jaen.

But before he could make these acquisitions, the citizens of Cadiz had universally taken the patriot side; the commander of the French vessels had been forced to surrender them; and the place, having opened a communication with the English fleet, assumed a posture of determined defence.

General Castanos, the Spanish commander in that province, meanwhile, having held back from battle until his raw troops should have had time to be disciplined, began at length to threaten the position of the French.

Jaen was attacked by him with such vigour, that Dupont was fain to evacuate it, and fall back to Baylen, where his troops soon suffered severe privations, the peasantry being in arms all around them, and the supply of food becoming from day to day more difficult.

On the 16th of July, Dupont was attacked at Baylen by Castanos, who knew from an intercepted despatch the extent of his enemy's distress: the French were beaten, and driven as far as Menjibar.
They returned on the 18th, and attempted to recover Baylen; but, after a long and desperate battle, in which 3000 of the French were killed, Dupont, perceiving that the Spaniards were gathering all around in numbers not to be resisted, proposed to capitulate.