It's funny seeing people react to this, because yes, what he's referring to is WWI and WWII here. Infamously, due to the events and processes of early 20th century, between 1912 and 1918 Serbia lost 1/3 (one-third) of its population, and was a victim of genocide in the other.
WW1 beats it actually - WW2 has tons of narrative "moments", but actually 1943-1945 is just one big post-arc slog to finish off two foregone conclusions.
Meanwhile WW1 has an insane third-act twist of Russia out/US in, and a Final Big Battle before it all falls apart in months.