Having been given command of the Regiment of Light Infantry Volunteers of Spain in August 1807, he refused to obey orders to join French General Dupont's forces, and instead marched his regiment to Extremadura, for which he was promoted to brigadier in June 1808 by the local Junta. By October that year, Henestrosa was leading the 2nd Division of Galluzo's 12,800-strong Army of Extremadura, an army which the following month, then under the command of the Conde de Belvedere, would be routed at Gamonal.