War is the Enemy of Art

Enemy of real art, not propaganda disguised as such.  Hermann Hesse, in an essay just after the start of the Great War:

Among our writers and men of letters there are, I believe, few if any whose present utterances, spoken or written in the anger of the moment, will be counted as their best work.  Nor is there any serious writer at heart who prefers Korner's patriotic songs to the poems of Goethe who held so conspicuously aloof from the War of Liberation.

Hesse remarks further that the "super-patriots" really do hold Goethe quite out of favor in their militaristic atmosphere, which is very much the point.  War ruins art and the warlike mentality degrades our ability to appreciate it.