On this day 110 years ago, French and British forces along the Marne River were suffering through arguably the most important battle of World War I – an early clash that saved Paris and broke the German war plan but also ushered in the horrors of trench warfare.
In an exclusive interview for GZERO World, UN's top diplomat Secretary-General António Guterres tells Ian Bremmer that he fears that world leaders today are making the same mistakes that got us into WWI.