Between April 30th 1939 (when the New York's World Fair opened) and the November 20th 1945 (when the Nuremberg Trials opened) a lot of water (together with a lot of blood and brains) flowed under one of Modern civilization's few remaining un-bombed bridges : call it WWII.
If to the bemused Theodor Adorno, New York's fair was Modernity's bizarre apogee , he also saw Nuremberg's trials as Modernity's appalling nadir.
But I doubt that even Adorno and his co-conspirator Max Horkheimer had really expected Modernity to soar , burn and crash just that quickly.