What was the effect of World War I on art?

World War I was such a traumatic event for Europeans that it shook the foundations upon which Western culture and civilization were based. People who witnessed the horrors of the conflict struggled to accept that the world was a rational place ruled by a just and caring God. Equally, they witnessed how science and technology had been harnessed to kill other people. So the art and literature of the postwar era reflected the disillusionment of many people, especially intellectuals. This took several forms. Some, like German artist Otto Dix, produced works that depicted the horrors of war in grisly detail. Others, like Pablo Picasso, rejected artistic (and by implication, political and social) conventions through abstract imagery and forms. Still others, like Dadaists, took the subversion of the traditional to extremes, producing absurdist paintings, sculptures, and poetry devoid of discernible meaning. Marcel Duchamp, for example, submitted a urinal turned upside down to an artistic society as a piece entitled Fountain. In a world where humans had slaughtered one another wholesale for no apparent reason, the conventions and rules of Western society no longer seemed worthy of attention by artists.
https://www.cnn.com/2014/10/30/opinion/merjian-art-modern-wwi/index.html