Great War

The pan-European military conflict. The same losses, although Austro-Hungary remained the empire, losing some territories in favour of Poland and Czechoslovakia (they kept Hungary, east of Slovakia, southern Ukraine, domains on the Balkan Peninsula). Germany turns into Weimar Republic, losing Polish territories. Russia is in chaos after the October Revolution (Poland and Finland simply set their borders and hope for the best). France remains the elective monarchy, Britain is well.