In November 1809, age 16, Espartero enlisted to the Regiment of Infantry "Ciudad Rodrigo" in Seville, seat of the Central Supreme Junta. Barely 9 days after his enlisting, he took part in the Battle of Ocaña, a defeat to the French Imperial Army. He joined the Military Academy of the Island of León in September 1810, and he was poised to join the Corps of Engineers thanks to his skills on maths, technical drawing, fortification and military tactics, but, following a setback in an examination, he was returned to the infantry in 1813.