There are two academic puzzles in dating the ending of the Enlightenment Project precisely to 1945.
One was that 1945 was supposed to be year of the Enlightenment's greatest success, not failure --- you remember, beating back the Nazi forces of darkness and barbarism etc.
The other was that 1945 had no great book and no great thinker proclaiming the end of one intellectual age and the birth of another.
No opus from no new Hume, Kant, Hegel or Newton, Galileo and Darwin.
Instead we had doctors Mengele and Dawson, operating from the opposite ends of the moral spectrum, putting the post into modernity.
Both men of deeds, not of words.
Doers - not thinkers - doing in the thinkers' Enlightenment Project : I kinda like that....