The Battle of Castelfidardo was fought on 18 September 1860, at Castelfidardo, a small town in the Marche region of Italy; the Piedmont army, acting as the driving force in the war for Italian unification, won a famous battle against papal troops. As a result of this battle, the Marches and Umbria entered in the Kingdom of Italy and the extent of the papal states was reduced to the area of what is today known as Lazio. The Franco-Belgian battalion gave rise to a Papal Zouave corps.