Henry Darger began working as a janitor at St Joseph’s Hospital in Chicago, from his escape from a juvenile mental hospital in 1909 until he left St Joseph’s because of his dislike of a particularly authoritarian nun. But he was drafted into the army in 1917. He was first stationed at Camp Grant in Rockford, Illinois, and then moved to Camp Logan near Houston, Texas. He had some kind of eye trouble, however, and was discharged before he could be sent overseas.
He was an obsessive collector of newspapers for much of his life, and reports of the First World War may have contributed gruesome elements to his work on In the Realms of the Unreal, which he began, probably, in 1912.
For the above I am grateful to Klaus Biesenbach, ed. Henry Darger (Munich et al: Prestel, 2009), 272-73.