I'm divided between 1930's World War I, more for all the ongoing issues with Austria Hungary and Russia, but I voted for Italy joining the Central Powers: France has to divide very few parts of their forces in order to counter the Italian offensive in the Alps (that fails, but it's still a pain for the Entente), Libya gets overwhelmed by Brits in Egypt, and the Ottomans, still upset for the 1912 overtaking of Cyrenaica by the Italians, joins the Allies. Maybe an alternate Gallipoli campaign in the gulf of Naples?