The January 2015 issue of Gramophone magazine had a short feature on Carl Nielsen’s fifth symphony. One of my best friends, a professional musician, introduced me to this symphony as he was doing research on the Danish composer. I used to play portions of the first movement during my course on Europe After Napoleon at IU Southeast, during the section on the early twentieth century, although I think Nielsen was (similarly to R. Vaughan Williams’ sixth symphony) expressing human duality rather than a lead-up to war or war itself.
I like the whole symphony but that first movement has always been a favorite. Writer Alan Gilbert discusses “the work’s sparse, pregnant opening... The two-note ostinato in the violas conitnues… soil from which the wind themes, delicate and ominous, emerge like flowering weeds” (p. 42). Part of that opening is a section for snare drum. Once the ominous opening segues into “the first movement’s major-key Adagio passage... ushered in by the most innocent of gestures on a pastoral oboe” (p. 42), one listens along with pleasure until “in bar 324... two flutes suddenly become possessed by that niggling motif from earlier.... Soon it starts to infect the whole orchestra, leading to one of the most extraordinary confrontations in the 20th-century symphony,” when the snare drum begins to improvise and disrupt everything else (p. 42).
Gilbert quotes Nielsen scholar Daniel Grimley that the symphony “tells you something about the world we’re living in today, when challenges and evil rear their ugly heads in unexpected ways. If the end of the snare drum was a total victory, then we’d be at the end of the symphony, but there’s still the second movement to go. How timely is that? We think we’re going to have resolution and peace and accord, yet somehow there’s still something to fight with---always” (p. 43).
Here's Leonard Bernstein's recording: https://www.youtube.com/watch?v=y6o3JnyVRCw