Second Italian War of Independence

The Second Italian War of Independence was fought by the Second French Empire and the Kingdom of Sardinia against the Austrian Empire in 1859 and played a crucial part in the process of Italian Unification. A year prior to the war, in the Plombières Agreement, France agreed to support Sardinia's efforts to expel Austria from Italy in return for territorial compensation in the form of the Duchy of Savoy and the County of Nice.

Source: Wikipedia — Second Italian War of Independence (CC BY-SA 4.0)