The Italian Co-belligerent Army (Esercito Cobelligerante Italiano), Army of the South (Esercito del Sud), or Italian Liberation Corps (Corpo Italiano di Liberazione) were names applied to the Royal Italian Army during the period when it fought on the side of the Allies during World War II, that is to say from September 1943 onwards. During the same period, the pro-allied Italian Royal Navy and Italian Royal Air Force were known as the Italian Co-belligerent Navy and Italian Co-belligerent Air Force respectively. From September 1943, pro-Axis Italian forces became part of the newly formed Italian Social Republic.