Juan Carlos de Aréizaga

Juan Carlos Aréizaga y Alduncín (1756–1820) was a Spanish military commander.

Many historians of the Peninsular War, including Gómez de Arteche, Toreno, Clonard and Oman, agree that, while not questioning Aréizaga's personal courage, he lacked the necessary skills required of a general.

Promoted to Fusiliers captain in August 1790, he saw action in the defence of Oran and remained garrisoned there until October 1791. which was victorious at Alcañiz towards the end of the month, and for which he was promoted to lieutenant general.

Based on the combined movements of the Duke of Albuquerque's Army of Extremadura, the Duke del Parque's Army of the Left and Aréizaga's new Army of the Centre, the Junta Central, contrary to Wellington's advice, had prepared a plan expel the French troops from Madrid. Aréizaga was routed by Marshal Soult at Ocaña, with about 4,000 Spaniards killed or wounded and 14,000 prisoners taken, as well as thirty flags and fifty of the sixty guns captured.

Following his overwhelming defeat, Aréizaga resigned, resignation that was not accepted, and he retreated down to Sierra Morena, where he was unable to prevent Soult from entering Andalusia and head towards Seville with seventy thousand troops, forcing the Supreme Central Junta to abandon that city and retreat down to Cádiz.

Having been flanked by Soult on 20 January 1810,

Post-war career With Fernando VII back on the throne, Areizaga was appointed captain general of Guipúzcoa in July 1814, and that same month the case against him for Ocaña was dismissed. He continued as governor until his death in 1820.

During the Hundred Days Areizaga was also given command of the Observation Corps of the Left (Ejército de Observación de la Izquierda) until June 1815, when he handed over his command to Enrique O'Donnell.