During the first worldwar the Austro-Hungarian empire used artists to make professional paintings of the war. These painters did not become part of the army but were paid by it for their services, they were called war painters or in German Kriegsmaler. Sometimes they were attached to a specific unit or a theatre of war.
In an album from my collection there are is a picture of a Kriegsmaler at work and also two pictures of the results of his work. Such pictures are hard to find.
For a portrait of an officer (in my collection) made by a Kriegsmaler go to this earlier blog.