The title comes from a quote of Churchill's. I agree with the sentiments in this Commentary post. Before the Great War Western civilization was confident and moving, advances in science, liberalization of trade, politics, and travel were all going in one direction. Afterwards, a disaster for many, many years, and as this link notes wound that is with us still.
Vienna before 1913 was a marvel. Paris and London in the Edwardian age glittered and pulsed. . Rhodes dream of a railroad from Cape to Cairo and pulling the whole world into the modern age along Western-lines, peacefully. Afterward, death haunted society, frivolity among the wealthy that would have appalled the always working Victorians, strange political movements runs by dicey, resentful men, the rise of protectionism and the seizure of the minds of elites by atheism and autocracy.
The last of the WWI veterans will probably die this year or the next. Fewer than a dozen live in all the world combined and they are all well over 100 years old. But they knew the old world before its passing and all will soon be gone.
Happy Veteran's Day.