In the middle of January 1810 the 3rd Battalion was posted to Spain. In June 1810 an Army of Portugal was formed under Masséna which was composed of three Army Corps. The two battalions of the Irish Legion became part of General Junot’s 8th Corps. Before joining with the Massena's main army, Junot was detailed to secure the flank of the Army of Portugal's intended advance by capturing the city of Astorga in the Province of León. They led the assault that took the city. During the battle, Captain John Allen's company's drummer boy continued to beat the charge after having lost both legs, for which he was given the French Legion of Honor. The Irish Battalions remained on active service with the Army of Portugal through the sieges of Ciudad Rodrigo and Almeida, the Battle of Bussaco and the full course of the advance to the Lines of Torres Vedras.