The war began in July 1914. But in 1909, five years before, Arnold Schoenberg composed his Five Pieces for Orchestra, op. 16 and, to my mind, they and other music from around this time, are like a premonition of the cataclysm to come.
How could Schoenberg sense the coming of a great disruption? Well, of course, I have no idea! But explain, if you would, how we got from the warm expressivity of Brahms' Clarinet Quintet of 1891:
to the tortured expressionism of Schoenberg's op 16 in just eighteen years? Or, even more surprising, how Schoenberg himself journeyed from the lush beauty of his Gurrelieder (begun between 1900 and 1903):
to the disturbing imagery and dissonance of his Pierrot Lunaire, op. 21, written in 1912, just two years before the war began? This video of No. 8, "Nacht" captures the eeriness quite well:
The monsters were indeed descending on Europe. But how did Schoenberg know?