April 26

Secret Treaty of London — Italy Enters WWI

Italy signed a secret treaty with Britain, France, and Russia promising to enter WWI on the Allied side in exchange for territorial gains in the Adriatic, South Tyrol, and colonial Africa. Italy declared war on Austria-Hungary the following month.

Italy's entry stretched Austrian forces and opened a new front in the Alps, but Italy's dismal military performance and dissatisfaction with postwar territorial settlements fueled the fascism that brought Mussolini to power.