De la Unión built a chain of 90 redoubts running from Sant Llorenç de la Muga to the coast. The lines were designed to protect the Alt Emporda from French invasion, but were manned by troops of uneven quality. The best units were the Spanish Guard and Walloon Guards, with three battalions each. Regular line infantry and provincial militia also manned the defenses.
The French blow fell in the early hours of 17 November and the Battle of the Black Mountain ensued. On the first day, the French gained ground on the western flank, but were repulsed in the center and on the eastern flank. A Spanish artillery shell killed Dugommier on the 18th and his successor Dominique Catherine de Pérignon ordered a temporary halt in the fighting. On 20 November, Pérignon resumed the attack and the French rapidly broke through the first and second Spanish lines. The French assaulted the 25-gun Notre-Dame-del-Roure redoubt for three hours, finally seizing the key position at 3:00 PM.[7] Arriving at Pont de Molins, de la Unión led a counterattack by 1,300 cavalry against two brigades of French infantry. During the subsequent struggle, he fell, fatally hit by two bullets.[8]
The battle ended in a rout of the Spanish army. The French inflicted 10,000 casualties on the Spanish, while suffering only 3,000 losses.[9]Jerónimo Girón-Moctezuma, Marquis de las Amarillas succeeded to the army command and retreated south of the Rio Fluvià where he was unable to save the fortress of San Fernando from capture. Girón was soon replaced in command by José de Urrutia y de las Casas. Pérignon and Pierre Sauret successfully concluded the Siege of Roses in early February.[10] The Peace of Basel ended the conflict in July 1795.