Having been promoted to Fusilier captain in 1805, following the Dos de Mayo Uprising that took place in Madrid on 2–3 May 1808, Bassecourt managed to escape to Andalusia where he was given the task of forming a new battalion of Walloon Guards from the non-French prisoners taken at the Battle of Bailen.

[1] Alongside the Duke of Alburquerque, Bassecourt fought at the actions of Mora and Consuegra (18 and 22 February 1809), before incorporating his troops into the Army of Extremadura the following month.

[1] Bassecourt was briefly given command of the remainder of the Army of Extremadura[1] the following September, when Francisco de Eguía marched off with three divisions of infantry and twelve or thirteen regiments of cavalry, some 25,000 men in all, to join Venegas's Army of La Mancha, a united force now exceeding 50,000 sabres and bayonets, with which the Junta intended to take Madrid.

[1] Having established his headquarters at Castellón, he set off to relieve Tortosa, but on his way there was defeated at Ulldecona (26 November 1810), losing over 2,500 troops, and was forced to withdraw to Peñíscola.

Reinforced by José Pascual de Zayas y Chacón's division, Bassecourt then forced the French troops to withdraw back to Cuenca.

[1] Confined to barracks at Salamanca when the Constitution was declared by the Trienio Liberal (1820–1823), he was appointed commander-in-chief of the province when the Duke of Angoulême's Hundred Thousand Sons of Saint Louis entered Spain.